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1. 3 21 Introduction s isare REI REESE EE hale ba ores PEGG E 3 2 2 PeakForce QNM Principles of Operation 3 2 2 1 Peak Force Tapping Mode cc ccc cece cece cece nnn 3 2 2 2 The Heartbeat a eh 4 2 2 9 HOTES CUNY CS Quis ie vare eR re eR WOO Res 4 2 3 PeakForce QNM Probe Selection 5 2 4 Basic PeakForce QNM 5 2 4 1 Select the Microscope cc cc cece cece eee n eee 5 2 4 2 Configure the Hardware ccc cece ee cece cece eee eee eee 6 2 4 3 Select Mode of Operation cece ee cece cece een nnn 7 2 4 4 Head Cantilever and Sample 8 DAS dove Ga scat hn Seat 9 2 4 6 Adjust Photodetector cc cece a a 9 2 4 7 Set Initial Scan 10 DAB ErngaBes usse he ER ie Sele oie shale Rugs 12 24 9 Tape the samplezossecve os ETE uk Shore Faces UE 12 2 5 PeakForce QNM Channels cece cece cece cece rece cence 15 25D DMT Modulus ase dee rA e AeA CR xa Fe RR 15 2 5 2 Log DMT Modulus ccc cece cece cece enn nnn 16 2 53 Adhesion vs o sr eni em cR dees RR RE es ae Oe 17 2 5 A Peak Force ales Fehr preme eie aee a ex R
2. Image A Equation 071 image A 0 00 Uri Maia in MPa 80 PeakForce QNM Rev F Offline Analysis Image Math The Image Math interface is shown in Figure 5 6c and the corresponding equation appears in Figure 5 6d Figure 5 6 The Image Math interface Image Image 3m 5 sh 24nN Channel 3 Scaling Factor 0 707 L unit MPa Image B Image B Unit Matrix Channel B 1 Scaling Factor B 0 00 L Operator B Output L Error No Error Figure 5 6d The Image Math equation Equation 0 71 Image 0 00 Unit Matrix in MPa Rev F PeakForce QNM 81 Offline Analysis Image Math 82 PeakForce QNM Rev F Index A Adhesion 17 Auto Config 23 25 26 38 39 40 C Cantilever 2 Cantilever Parameters 29 66 Capture 36 Capture Line 37 Channels 15 Configure Experiment 42 D Deflection Limit 31 35 Deflection Sensitivity 56 76 Deformation 22 Deformation Fit Region 28 35 Deformation Sensitivity 76 Display Mode 79 Dissipation 20 Dissipation Limit 30 35 DMT model 15 DMT Modulus 15 DMT Modulus Limit 30 35 E Engage 12 Expanded Mode 41 Exported Force Curves 76 Exporting Force Curves 76 F Feedback Gain 24 34 Feedback Parameters 23 Force Curve Selection box 72 Force Limit 30 35 H Hsdc 69 Display Channel 76 I Image Math 79 L Lift Height 26 35 Limits 30 Limits Parameters 31 Load Image 70 LogDMT Modulus Limit
3. Analog3 Analoga CM LP Deflection Bw 40 00 kHz LIE Scanasyst Setup Allow Noise Threshold 0 500 nm Scan amp syst AutoConfig Frar 0 CHIM Scan amp syst Auto Control On BE PeakForce QNM Control OM Peak Force Amplitude 150 nm Lift Height 300 nm OC Top Fit Region 10 X OC unload Fit Region 70 COC Deformation Fit Region 855 B Cantilever Parameters i Spring Constant 0 3000 N m Tip Radius 10 0 nm L v v Sample Poisson s Ratio 0 300 B PeakForce QNM Limits OM Force Limit 24 58 V OM Dissipation Limit 1024 Arb DMT Modulus Limit 1024 Arb OC LogdMT Modulus Limit 32 00 log Arb LOC LogDMTModulus Offset Olog Arb E Limits LIE z Limit 8 957 um Z Range 7 42 um LOM Deflection Limit 24 58 V Other v Show Parameter List 1 Show Parameter List 2 Configure Lists v Show All The checked parameters display in normal Real time mode while those parameters without a will not display in normal Real time mode 44 PeakForce QNM Rev F PeakForce QNM Operation Advanced Atomic Force Operation Check the parameters that you want displayed and right click in the Scan Parameter List and select SHOW ALL items to hide the unchecked parameters The panel will once again appear in normal Real time mode Rev F PeakForce QNM 45 PeakForce QNM Operation Advanced Atomic Force Operation 46 PeakForce QNM Rev F Chapter3 PeakForce QNM Samples Five sampl
4. Tip radius may be measured using a tip characterizer sample and the Tip Qualification function in NanoScope Analysis software NanoScope software does not include the Estimated End Radius function 1 Scan PEAK FORCE QNM IN AIR mode the characterizer sample Set the Scan Size to approximately 1 5um Characterizer image size is important because along with Tip Image Size and feature density it determines how many peaks are used for the tip estimation Set the Samples Line and Lines to 512 Set the Aspect Ratio to 2 0 Set the Scan Rate to 0 5 Hz or less Because this is an intentionally rough sample that can damage the probe tip set ScanAsyst Noise Threshold to 1 0 nm CAPTURE the characterizer image Open the Height channel of the saved image in the NANOSCOPE ANALYSIS package 62 PeakForce QNM Rev F Calibration Measure the Tip Radius 8 Flatten the image by clicking the PLANE FIT icon 9 Select XY as the Plane Fit Mode 10 Select 1ST AS the Plane Fit Order 11 Click EXECUTE to plane fit the image See Figure 4 5a Figure 4 5a Plane Fit of the Characterizer Sample B Inputs Plane Fit Mode Plane Fit Order 2nd Plane Fit Z Threshold Direction No thresholding Plane Fit Z Threshold Percent 00 Add Higher Order off Rev F PeakForce QNM 63 Calibration Measure the Tip Radius 12 Click the TIP QUALIFICATION icon in the NanoScope Analysis toolbar to open the Tip Qualification
5. gt lt BROKER gt lt PeakForce QNM User Guide Copyright O 2009 2010 2011 Bruker Corporation 004 1036 000 All rights reserved Document Revision History PeakForce QNM User Guide Ref Revision Date Section s Affected DCR Approval F June 3 2011 3 3 Vinson Kelley E April 12 2011 1 2 2 3 Vinson Kelley D 01 24 2011 Re branded R Wishengrad C May 26 2010 Added Fig 4 5b section 5 6 Vinson Kelley B March 03 2010 2 4 9 Vinson Kelley A January 22 2010 Initial Release N A Vinson Kelley Notices The information in this document is subject to change without notice NO WARRANTY OF ANY KIND IS MADE WITH REGARD TO THIS MATERIAL INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE No liability is assumed for errors contained herein or for incidental or consequential damages in connection with the furnishing performance or use of this material This document contains proprietary information which is protected by copyright No part of this document may be photocopied reproduced or translated into another language without prior written consent Copyright Copyright 2004 2011 Bruker Corporation All rights reserved Trademark Acknowledgments The following are registered trademarks of Bruker Corporation All other trademarks are the property of their respective owners Product Names NanoScope MultiMode D
6. Feedback Gain 5 000 L ScanAsyst Auto Control On B Cantilever Parameters k Spring Constant 0 3000 N m Tip Radius 10 0 nm L Sample Poisson s Ratio 0 300 B PeakForce QNM Limits L pMTModulus Limit 1024 Arb B Limits L z Range 7 42 um B other L Units Metric 40 PeakForce QNM Rev F PeakForce QNM Operation Advanced Atomic Force Operation Expanded Mode 1 The EXPANDED MODE view shown in Figure 2 9b increases the number of displayed parameters enabling expert users to fine tune an image Figure 2 9b The EXPANDED MODE view of the Scan Parameter List for ScanAsyst in Air EH Scan Scan Size Aspect Ratio X Offset Y Offset Scan Angle Scan Rate Tip velocity Samples Line Lines Slow Scan Axis L xy Closed Loop EH Feedback Peak Force Setpoint Feedback Gain LP Deflection BW ScanAsyst Noise Threshold L Scan amp syst Auto Control B PeakForce QNM Control H Peak Force Amplitude L Lift Height EB Cantilever Parameters E Spring Constant Tip Radius L sample Poisson s Ratio B PeakForce QNM Limits Force Limit Dissipation Limit L pMTModulus Limit B Limits H z Range L Deflection Limit B Other LP Deflection Tip Bias Control Sample Bias Control units Minimum Engage Gain Peak Force Engage Setpoint Bidirectional Scan Tip Serial Number Output 1 Data Type L Output 2 Data Type 500 nm 1 00 0 000 nm 0 000 nm 0 00 9 0 977 Hz 0 977 um s 512 512 Enabled 0 1000 V 5 000 40 00 kHz 0 500 nm On 150 nm 300
7. W Feaz F is the interaction force vector and dZ is the displacement vector Because the Z motion and the velocity reverse direction in a half cycle the integral is zero if the load and unload curves coincide The dissipation is therefore the hysteresis between the load and unload curves Pure elastic deformation has no hysteresis which corresponds to very low dissipation Energy dissipated is displayed in electron volts as the mechanical energy lost per tapping cycle The Dissipation channel plots the dissipated energy in each cycle by integrating the area between the Trace load or extend and Retrace unload or retract curves as shown in the blue area in Figure 2al Figure 2 5h Dissipation shaded area in a polystyrene PS and Low density polyethylene LPDE blend 30 20 Force nN 150 160 170 180 190 Z Height nm 20 PeakForce QNM Rev F PeakForce QNM Operation PeakForce QNM Channels Figure 2 51 shows the dissipation image of a PS LDPE blend Figure 2 51 Dissipation image of a PS LDPE blend 2 Rev F PeakForce QNM 21 PeakForce QNM Operation PeakForce QNM Channels 2 5 6 Deformation The maximum deformation of the sample defined as the distance from the base of the Deformation Fit Region position to the peak interaction force position caused by the probe See Figure 2 5 Figure 2 5k shows a deformation map of a PS LPDE blend Note The total deformat
8. high force sensitivity Therefore cantilever stiffness should be selected based on the sample stiffness Bruker s recommendations are shown in Table 2 3a Table 2 3a Recommended Probes Nominal Sample Modulus E Probe Spring Constant k 1 MPa E 20 MPa ScanAsyst Air 0 5 N m 5 MPa lt E lt 500 MPa Tap150A P N MPP 12120 10 5 N m 200 MPa E 2000 MPa Tap300A RTESPA P N MPP 11120 10 40 N m 1 GPa lt E lt 20 GPa Tap525A P N MPP 13120 10 200 N m 10 GPa lt E lt 100 GPa DNISP HS 350 N m Note The recommended spring constants are general guidelines that reflect a compromise between image resolution and modulus accuracy E g a stiff cantilever will improve modulus accuracy at the expense of damaging the sample To reduce optical interference probes should be coated on their back side You may purchase these probes from Bruker Probes http www brukerafmprobes com 2 4 Basic PeakForce QNM Operation This section describes how to perform a simple PeakForce QNM experiment Later sections will discuss PeakForce QNM parameters and their influence on the measurements 2 4 4 Select the Microscope Follow the Select Microscope procedure described in your microscope Instruction Manual Rev F PeakForce QNM 5 PeakForce QNM Operation Basic PeakForce QNM Operation 2 4 2 Configure the Hardware 1 Ifyou have a MultiMode set the mode selector switch on the MultiMode base to A
9. 16 Figure 2 5c Adhesion on PS LDPE 17 Figure 2 54 Adhesion map of a PS LDPE blend 17 Figure 2 5e The heartbeat Force vs 18 Figure 2 5f Force curve Force vs 18 Figure 2 5g Peak Force Error map of a PS LDPE blend 19 Figure 2 5h Dissipation shaded area in a polystyrene PS and Low density polyethylene LPDE blend 20 Figure 2 51 Dissipation image of a PS LDPE 21 Figure 2 5 Deformations 22 terae kw ee repe PER PEIUS 22 Figure 2 5k Deformation map ofa PS LDPE 23 Figure 2 DMT Fit regions of the Force 27 Figure 2 6b DMT Fit regions ofthe Force 28 Figure 2 6c Illustration of PeakForce QNM 30 Figure 2 6d SPM engage step eee ee eee eee tone tosse 32 Figure 2 7a CAPTURE LINE 36 Figure 2 7b High speed data capture is complete However the data is not immediately transferred to the PC 37 Rev F PeakForce QNM vii List of Figures Figure 2 8a The heartbeat and force curves of an image before left and after right AUTO CONFIG correction 38 Figure 2 8b The AUTO CONFIG 39 Figure 2 9a The SIMPLE MODE view of t
10. PDMS Soft 2 sample le OQ elo 60MPa oo 3 DMTModdus 100m Rev F PeakForce QNM 49 PeakForce QNM Samples Polystyrene 3 3 Polystyrene Nominal modulus 2 7 GPa This polystyrene sample is spin cast on a silicon wafer Suggested probes RTESPA Tap300 or Tap525 A typical force curve of this sample is shown in Figure 3 3a and an image of the modulus is shown in Figure 3 3b The standard deviation of the modulus in this image is 0 2 MPa Figure 3 3a Typical force curve of a Polystyrene sample Force nN 20 40 60 80 100 120 140 160 180 Z nm Figure 3 3b Typical modulus image of a Polystyrene sample oC IMS OMTModsus 50 PeakForce QNM Rev F PeakForce QNM Samples HOPG 3 4 HOPG Highly Oriented Pyrolytic Graphite Nominal modulus 18 GPa Suggested probes TESPA diamond A typical force curve of this sample is shown in Figure 3 4a and an image of the modulus is shown in Figure 3 4b The standard deviation of the modulus in this image is 2 MPa Figure 3 4a Typical force curve of a HOPG sample 400 300 200 100 Force nN 50 100 1 0 250 300 50 20 Z nm Figure 3 4b Typical modulus image of a HOPG sample MQ a 2706P 1 o0 3 OMT Modus 10m Rev F PeakForce QNM 51 PeakForce QNM Samples Fused Silica 3 5 Fused Silica Corning 7980 fused silica Nominal modulus 72 9 GPa Suggested probe Diamond 52 Pe
11. QNM Rev F Calibration Calibrate the Deflection Sensitivity 4 Select PEAKFORCE QNM IN AIR in the Select Experiment panel and click LOAD EXPERIMENT 5 Set the Scan Size to 0 nm 6 ENGAGE the probe onto a clean sapphire required for cantilevers with k gt 200 N m or silicon surface using the PeakForce QNM in Air mode 7 Activate RAMP mode by clicking the RAMP icon in the Workflow Toolbar This causes the system to stop scanning and the probe to position above the center of the previous image ti 8 Enter the following parameter settings in the designated panels of Ramp Parameter List a Inthe Ramp panel select Parameter Setting Ramp output Z Ramp size 100nm 1 00um Scan Rate 1 00Hz Number of samples 512 b Inthe Mode panel select Parameter Setting Trigger mode Relative Trig threshold 0 2V c Inthe Channel 1 panel select Parameter Setting Data Type Deflection Error X Data Type Z Display Mode Deflection Error vs Z Ww 9 Click the RAMP SINGLE icon on the NanoScope toolbar or select Ramp gt Ramp Single from the menu bar Rev F PeakForce QNM 57 Calibration Calibrate the Deflection Sensitivity 10 Move two cursors onto the Deflection vs Z plot see Figure 4 3b 11 Arrange the cursors so that they surround the contact steepest portion of the graph see Figure 4 3b Figure 4 3b Force Cu
12. QNM Operation PeakForce QNM Parameters Deformation Fit Region The Deformation Fit Region of the load force curve shown in Figure 2 6b is excluded from the Deformation channel display This parameter is used to reduce the effect of baseline noise Range and Settings 50 100 100 is defined as the force between the zero force point and the peak force in the load curve Typical 85 The portion of the force curve above the 85 point is displayed in the Deformation channel Figure 2 6b DMT Fit regions of the Force curve Deformation Fit Region Force nN Deformatio 10 20 30 40 50 60 70 80 lal Separation nm PeakForce QNM Rev F PeakForce QNM Operation PeakForce QNM Parameters 2 6 3 Cantilever Parameters The following parameters are needed to calibrate PeakForce QNM Spring Constant Measure the spring constant of the probe and input that value into this panel Spring constant may be measured using the Thermal Tune function in NanoScope software Refer to Calibrate the Spring Constant Using Thermal Tuning Section 4 4 for details Tip Radius Measure the tip radius and input the value in this panel Tip radius may be measured using a tip characterizer sample and the Tip Qualification function in NanoScope software Refer to Measure the Tip Radius Section 4 5 for details Poisson s Ratio Poisson s ratio of the sample This is used to calculate the sample modulus from the measure
13. collect an image and then at a region of interest during the capture click the CAPTURE LINE button This ensures capture of the raw high speed data capture HSDC in the DSP buffers Remember that to transfer the data to the computer and into a file you must click the UPLOAD DATA button in the High Speed Data Capture interface Procedure 1 Start the NanoScope Analysis package by double clicking the offline icon on the Windows desktop 2 Open the PeakForce QNM HSDC file Rev F PeakForce QNM 69 Offline Analysis Procedure a 3 Click the QNM Hsdc Force Curve Image icon to open the QNM Force Curve Image window shown in Figure 5 2a Figure 5 2a The QNM Hsdc Force Curve Image window Force nN 4 Click the LOAD IMAGE button circled in Figure 5 2a and select the image file associated with your high speed data capture file PeakForce QNM Rev F 70 Offline Analysis Procedure 5 The solid blue horizontal line shown in Figure 5 2b displays the captured line Figure 5 2b The HEIGHT channel of the image file e MI Ql al o 198 2 nm Captured Line o 0 0 1 Height Rev F PeakForce QNM 71 Offline Analysis Procedure 6 Two vertical dashed blue cursors shown in Figure 5 2c display the X position of the displayed force curves when PAIR is checked in the Force Curve Selection box The associated n
14. kit between the tip and sample Because the deformation depths and lateral forces are small there is minimal damage to the probe or sample 1 2 What is in the PeakForce QNM kit The PeakForce QNM kit consists of the following items 1 Software keys to enable PeakForce QNM in real time and off line operation 2 A pack of ten each of the following probes ScanAsyst Air e 150 P N MPP 12120 10 Tap300A RTESPA P N MPP 11120 10 e Tap525A P N MPP 13120 10 3 One pre mounted DNISP HS probe in the appropriate probe holder 4 PeakForce QNM samples Refer to PeakForce QNM Samples Chapter 3 for details 5 One day of PeakForce QNM applications training 1 3 Conventions and Definitions In the interest of clarity certain nomenclature is preferred An SPM probe is comprised of a tip affixed to a cantilever mounted on a substrate which is inserted in a probe holder Three font styles distinguish among contexts For example Window or Menu Item BUTTON OR PARAMETER NAME is set to VALUE 2 PeakForce QNM Rev F Chapter 2 PeakForce QNM Operation 2 1 Introduction This chapter describes how to perform a simple PeakForce QNM experiment Later sections will discuss PeakForce QNM parameters and their influence on the measurements 2 2 PeakForce QNM Principles of Operation 2 2 1 Peak Force Tapping Mode Peak Force Tapping mode the core technology behind PeakForce QNM and ScanAsyst modes performs a very fast
15. nm 0 3000 N m 10 0 nm 0 300 24 58 V 1024 Arb 1024 Arb 7 42 24 58 V Enabled Ground Ground Metric 10 0 0 1500 V Disabled Off Off PeakForce QNM 41 PeakForce QNM Operation Advanced Atomic Force Operation Show All 1 From the Menu bar click EXPERIMENT gt CONFIGURE EXPERIMENT This opens an information window shown in Figure 2 9c Figure 2 9 The Configure Experiment information window NanoScope You have enabled Modify Experiment mode You may now edit the Experiment configuration by adding deleting arranging and renaming items in the Workflow Toolbar 2 Click OK to open the Configure Experiment window shown in Figure 2 94 Figure 2 9d The Configure Experiment Window Configure Experiment Add Commands Probe Recommendations Withdraw L Tune Recommended Probe Holder Cl Generic Sweep sl L scM Tune Add Recommended Probes Remove Experiment Description PeakForce QNM in Air v Include Microscope Select Parameters Add RealTime Views Select this option if you would like to save the Torsion Harmonix EC Pot Sensor and Temp Controller values from the microscope select in the experiment 3 Checka box in the Add Commands panel to add that command to the Workflow Toolbar 4 Click OK to accept your choices and close the Configure Experiment window 42 PeakForce QNM Rev F PeakForce QNM Operation Advanced Atomi
16. sample modulus and can be approximated as infinite and calculate the sample modulus using the sample Poisson s Ratio Poisson s ratio generally ranges between about 0 2 and 0 5 perfectly incompressible giving a difference between the reduced modulus and the sample modulus between 4 and 25 Because the sample s Poisson s ratio is not generally known many publications report only the reduced modulus Entering zero for this parameter will cause the system to return the reduced modulus Recommended values for the sample s Poisson ratio V are shown in Table 4 6a Table 4 6a Recommended values of the sample Poisson s ratio V as a function of the sample stiffness Vs E lt 100 MPa 0 5 0 1 lt E 1 GPa 0 4 1 GPa lt lt 10 GPa 0 3 4 6 1 Cantilever Parameters After you have measures the cantilever Spring Constant and the Tip Radius enter them into the Cantilever Parameters panel in the Scan Parameters window of the NanoScope software window shown in Figure 4 6a If available enter the Sample Poisson s Ratio Figure 4 6a The Cantilever Parameters panel B Cantilever Parameters Spring Constant 0 3000 Tip Radius 10 0 nm L Sample Poisson s Ratio 0 300 4 6 2 Feedback Parameters Peak Force Setpoint A Peak Force Setpoint that is too high can either damage the sample or wear the tip It is generally desirable to reduce the Peak Force Setpoint to as small a value as is
17. window 13 Enter the measured average Deformation see Deformation Section 2 5 6 into the Height 1 from Apex field Note The Height from Apex parameter should equal the average penetration depth or the indentation in the force curve The indentation can be measured as the separation from the minimum force to the peak force in the loading curve For most samples the indentation is very close to the sample deformation Therefore the average deformation can be used as Height from Apex parameter to estimate tip radius But for very soft samples lt 20MPa the adhesion is very large and the difference between indentation and deformation is large so that the indentation must be measured from the force curves in the Force Monitor window shown in Figure 4 5b Figure 4 5b Typical force curve of a PDMS Soft 1 sample Nominal modulus 2 5 MPa 1 Force nN Indentation 14 Click ESTIMATE TIP 15 Click QUALIFY TIP Figure 4 5c displays the Estimated Tip End Radius 64 PeakForce QNM Rev F Calibration Calibrate Peak Force QNM Figure 4 5 Tip Qualification Results D Pests 7 345 tm 1 Aspect Ratio 1 00 Number of Peaks in 1 Estimated End Rags 3 3 849 nm emo 14 44 tm ETD 2 Aspect Ratio 0 967 Nube of Peaks in 102 1 Estimated End Radhus 7 605 nm r states suspect Sigma Mult for Spike Rejection 2500 pem L signa for Dit
18. 30 35 LogDMT Modulus Offset 30 35 Low Pass Deflection Bandwidth 24 34 M Medium 33 Modulus 65 N NanoScope Analysis 76 O Offline analysis 69 Optimization 38 P Parameter Visibility 34 Peak Force Amplitude 26 35 Peak Force Engage Setpoint 32 Peak Force Setpoint 23 34 PeakForce QNM Channels 15 PeakForce QNM Control Parameters 26 Plot Units 78 Poisson s Ratio 29 35 Probe 2 Probe Holder 2 Probetip 2 5 ScanAsyst 1 ScanAsyst Auto Config Frames 25 34 ScanAsyst Auto Control 25 34 ScanAsyst Auto Gain 25 34 ScanAsyst Auto Setpoint 25 34 Rev F PeakForce QNM 83 Index ScanAsyst Auto Z Limit 34 ScanAsyst Noise Threshold 24 34 ScanAsyst Scan Auto Scan Rate 25 34 ScanAsyst Setup 23 24 34 Select Experiment 7 56 Show All 42 Simple Mode 40 Spring Constant 29 35 76 Substrate 2 T Thermal Tune 59 Time Domain Plots 77 Tip 2 Tip Radius 35 62 Top Fit Region 27 35 Torsional Q 29 U Unload Fit Region 27 35 Upload Data 37 Y Young s modulus 15 54 66 79 Z Z Limit 31 35 Z Range 31 35 84 PeakForce QNM Rev F
19. 4 Practical Advice on the Determination of Cantilever Spring Constants 1 Ensure that the probe is withdrawn adequately from the sample before activating THERMAL TUNE The probe should not interact with the sample during its self excitation under ambient conditions 2 Click CALIBRATE gt THERMAL TUNE or the THERMAL TUNE icon in the NanoScope tool bar shown 3 Select a frequency range that includes the resonant frequency of the cantilever See Figure 4 4a Stiff cantilevers may require the 5 2000 kHz range Figure 4 4a Select Thermal Tune Frequency Range Thermal Tune Range 1 100KHz PSD Bin Width 1 100 KHz Deflection Sensitivi 5 2000 KHz Deflection Sensitivity Corre 1 08 Temperature Celsius 21 0 Spring Constant 0 06780 L Median Filter Width 3 1 See http www ampc ms unimelb edu au afm calibration html Rev F PeakForce QNM 59 Calibration Calibrate the Spring Constant Using Thermal Tuning 4 Click ACQUIRE DATA in the Thermal Tune panel shown in Figure 4 4b Figure 4 4b The Thermal Tune panel Thermal Tune E3 Thermal Tune PSD Power pm Hz 10 15 20 25 30 35 40 El Frequency kHz Thermal Tune Computation Done eed Weis Lorentzian Air O Simple Harmonic Oscillator Fluid Thermal Tune Status B Thermal Tune Thermal Tune Range 5 2000KHz PSD Bin Width 47 7 Hz Deflection Sensitivity 46 10 nm V Deflection Sensi
20. FM amp LFM See Figure 2 4a Figure 2 4a Mode selector switch Red Contact Green Tapping Mode selector switch 6 PeakForce QNM Rev F PeakForce QNM Operation Basic PeakForce QNM Operation 2 4 3 Select Mode of Operation 1 Click the SELECT EXPERIMENT icon This opens the Select Experiment window shown in lt Figure 2 4b Figure 2 4b The PeakForce QNM in Air Select Experiment window Select Experiment Dimension Icon t3 Select From Microscope Dimension Icon Use previous experiment PeakForce QNM in Air 11 27 09 22 05 Or Choose an Experiment Category Scan Asyst lt 2 I ScanAsyst Tapping Contact Mode Mode 2 o LS Electrical amp Mechanical Other SPM Magnetic Properties je gt gt Change Microscope Setup o Select Experiment Group Force Moduluation Force Volume PeakForce is a groundbreaking atomic Nanoindentation force microscope AFM imaging mode that Quantitative Nanomechanical Mapping provides AFM researchers unprecedented capability to quantitatively characterize nanoscale materials It rnaps and distinguishes between nanomechanical properties including modulus and adhesion while simultaneously imaging sample topography at high resolution PeakForce QNM operates over an extremely wide range i approximately 1 MPa to 50 GPa for modulus and e Select Experiment 10 to 10 uN for adhesion enabling Harmonix charac
21. Force QNM is quantitative and has high spatial resolution Peak Force Tapping Mode microscopy the core technology behind PeakForce QNM and ScanAsyst M is a new Bruker proprietary primary Atomic Force Microscopy AFM mode Other primary AFM modes include Contact Tapping Scanning Tunnelling Microscopy STM and Torsional Resonance modes Peak Force Tapping mode oscillates but far below the cantilever resonant frequency the vertical motion of the cantilever using the main Z piezo element and relies on peak force for feedback Peak interaction force and nanoscale material property information is collected for each individual tap Because Peak Force Tapping mode does not resonate the cantilever cantilever tuning is not required This is particularly advantageous in fluids Peak Force Tapping Mode includes auto optimization called ScanAsyst of scanning parameters including gains setpoint and scan rate This enables users to rapidly obtain high quality images ScanAsyst is intended to be the first choice imaging mode for NanoScope version 8 10 and later software Because Peak Force Tapping mode controls the applied force tip wear is reduced Peak Force Tapping mode imaging increases the resolution by controlling the force that the tip applies to the sample thereby decreasing the deformation depths this decreases the contact area Rev F PeakForce QNM Introduction to PeakForce QNM Microscopy What is in the PeakForce QNM
22. akForce QNM Rev F Chapter 4 Calibration 4 1 4 2 Introduction to Calibrating PeakForce QNM To quantify the forces as well as other mechanical properties of your sample it is important to understand the PeakForce QNM calibration procedure Note For best results the calibration process will need to be performed for each probe Absolute vs Relative Calibration Methods There are two methods of obtaining calibrated quantitative results from PeakForce QNM The first method the relative method avoids accumulated errors that can cause errors in modulus measurements but has the downside in that it requires a reference sample that can be measured by the same probe as the unknown sample The second method the absolute method does not require a reference sample but requires accurate measurement of the tip end radius typically by scanning an artifact sample like TipCheck and spring constant typically with thermal tune for soft cantilevers Both methods require measurement of the deflection sensitivity on a hard sample For both methods it is important to choose a probe that can cause enough deformation in the sample and still retain high force sensitivity Figure 4 2a shows the recommended probes and the modulus range over which they work best Rev F PeakForce QNM 53 Calibration Absolute vs Relative Calibration Methods Figure 4 2a Modulus ranges covered by various probes The modulus of the reference sampl
23. ation Basic PeakForce QNM Operation 2 4 7 Set Initial Scan Parameters Scan Panel In the Scan panel of the Scan Parameters List set the following initial scan parameters see Figure 2 44 1 Set the Scan Size 2 Set the Scan Angle Feedback Panel 1 Set ScanAsyst Auto Control to ON see Figure 2 4d Figure 2 44 PeakForce QNM in Air SIMPLE MODE Parameters Panel Scan Scan Size 500 nm Aspect Ratio 1 00 X Offset 0 000 nm Y Offset 0 000 nm Scan Angle 0 00 Scan Rate 0 977 Hz L Samples Line 512 B Feedback Peak Force Setpoint 0 1000 V Feedback Gain 5 000 ScanAsyst Auto Control On B Cantilever Parameters Spring Constant 0 3000 N m Tip Radius 10 0 nm L Sample Poisson s Ratio 0 300 B PeakForce QNM Limits L DMTModulus Limit 1024 Arb B Limits L 7 Range 7 42 um H Other L Units Metric 10 PeakForce QNM Rev F PeakForce QNM Operation Basic PeakForce QNM Operation Channels 1 Set the Channel 1 Data Type to HEIGHT SENSOR see Figure 2 4e 2 Set the Channel 2 Data Type to PEAK FORCE ERROR see Figure 2 4e 3 Set the Channel 3 Data Type to DMT MODULUS see Figure 2 4 Set the Channel 4 Data Type to LOGDMT MODULUS see Figure 2 4e 5 Set the Channel 5 Data Type to ADHESION see Figure 2 4e 6 Set the Channel 6 Data Type to DEFORMATION see Figure 2 4e 7 Set the Channel 7 Data Type to DISSIPATION see Figure 2 4e 8 Set Data Scale to a reasonable value for the sample or cli
24. atively large Peak Force Setpoint while performing AUTO CONFIG operations and reducing the Peak Force Setpoint later if necessary Rev F PeakForce QNM 23 PeakForce QNM Operation PeakForce QNM Parameters Feedback Gain The gain of the Peak Force Tapping feedback control loop Note Both Peak Force Setpoint and Feedback Gain are dynamically and automatically controlled when ScanAsyst Auto Control is set to ON Note A Feedback Gain that is too large will cause oscillation of the system and increase noise while too small a Feedback Gain will result in poor sample tracking Low Pass Deflection Bandwidth The low pass filter is used to reduce deflection noise Lower bandwidths will reduce noise but will distort the force curve and introduce errors in quantitative nanomechanical property measurements Range and Settings 10 kHz 65 56 kHz Default value 40 kHz ScanAsyst Setup Range and Settings NEVER Does not allow ScanAsyst Auto Control ALLOw Allows ScanAsyst Auto Control Note SHOW ALL discussed in the NanoScope Software Version 8 User Guide must be enabled to view and edit this parameter ScanAsyst Noise Threshold ScanAsyst Noise Threshold is linked to the Feedback Gain and is used to tune it Larger ScanAsyst Noise Thresholds will result in better sample tracking but increased oscillation noise Lower ScanAsyst Noise Thresholds will result in a cleaner image but the sample tracking will suffer Range and Sett
25. c Force Operation Figure 2 9e Select SHow ALL items Scan Scan Size Aspect Ratio X Offset Y Offset Scan Angle Scan Rate L samples Line Feedback Peak Force Setpoint Feedback Gain L scanAsyst Auto Control Cantilever Parameters Spring Constant Tip Radius L Sample Poisson s Ratio PeakForce QNM Limits L pMTModulus Limit Limits Lz Range Other L Units v Show Parameter List 1 Show Parameter List 2 Configure Lists Show All 500 nm 1 00 0 000 nm 0 000 nm 0 00 0 977 Hz 512 0 1000 V 5 000 On 0 3000 10 0 nm 0 300 1024 Arb 7 42 um Metric 5 Right click in the Scan Parameter List and select SHOW ALL shown in Figure 2 9e Rev F PeakForce QNM 43 PeakForce QNM Operation Advanced Atomic Force Operation This makes all Scan Parameters visible along with two check boxes the left green check box for the SIMPLE MODE and the right red check box for the EXPANDED MODE See Figure 2 9f Figure 2 9f Enable Parameters Sean Scan Size 500 nm Aspect Ratio 1 00 X Offset 0 000 nm With Y Offset 0 000 nm Parameter will Scan Angle 0 00 display Scan Rate 0 977 Hz Tip Velocity 0 977 um s Samples Line 512 o o Lines 512 Slow Scan Axis Enabled xY Closed Loop On Without Feedback Parameter will SPM Feedback Peak Force not display Lateral 16x Gain Disabled Peak Force Setpoint 0 1000 V Feedback Gain 5 000 OC Proportional Gain 0
26. ck the AUTOSCALE icon after engaging Note For example for a 200nm step height calibration sample a reasonable Data Scale setting is 300nm initially 9 Set Line direction to either TRACE or RETRACE Figure 2 4e Suggested PeakForce QNM Channel Settings Channel 1 Scan Scale 50 00 nm RT Plane Fit Line Data Type Height Sensor v Direction v Center 0 nm OL Plane Fit None Channel 2 Scan Scale 0 2000 V RT Plane Fit Offset Data Type Peak Force Error v Direction Retrace v Center QV OL Plane Fit None v Channel 3 Scan Scale 128 0 Arb RT Plane Fit None Data Type DMTModulus Direction Retrace Center 0 Arb OL Plane Fit None Channel 4 Scan Scale 32 00 log amp rb RT Plane Fit None Data Type LogDMT Modulus v Direction Retrace Center 0 OL Plane Fit None v Channel 5 Scan Scale 500 0 mV RT Plane Fit None Data Type Adhesion Direction Retrace Center QV OL Plane Fit None Channel 6 Scan Seale 101 1 nm Plane Fit None v Data Type Deformation v Direction Retrace Center OL Plane Fit None Channel 7 Scan Scale 16 00 Arb RT Plane Fit None Data Type Dissipation Direction Retrace Center 0 Arb OL Plane Fit None Rev PeakForce QNM 11 PeakForce QNM Operation Basic PeakForce QNM Operation 2 4 8 Engage 1 Select Microscope gt Engage or click the ENGAGE icon on the Workflow Too
27. contingity Rejection 1500 D Cross Section 1 Height 1 from Apex 5 000 res Min 10 00 Good ween TO1 Threshold 40 00 res Wom Bad Theeshold 50 00 Min y x aspect Ratio 1 0 250 Max yix Aspect Ratio t 2 000 B Cross Section 2 Height 2 from Apex 1040 nem Stow 25 00 tem Goods Ween 2 Threshold 40 0 Wormnzllad CTO Thewihold 50 00 re Min yix Aspect Ratio 2 0 280 I yrs aspect Ratio 2 20 Gemeente 46 Calibrate Peak Force Three parameters are needed to fully calibrate PeakForce QNM 1 Deflection Sensitivity See Calibrate the Deflection Sensitivity Section 4 3 fora procedure to measure this 2 Spring Constant See Calibrate the Spring Constant Using Thermal Tuning Section 4 4 for a procedure to measure this 3 Tip Radius See Measure the Tip Radius Section 4 5 for a procedure to measure this A fourth parameter the Sample s Poisson s Ratio is needed to convert the measured reduced modulus to the sample modulus The reduced modulus is related to the sample modulus by the following equation 1 l v E Mem E E 5 Rev PeakForce 65 Calibration Calibrate Peak Force QNM where V and are the Poisson s ratio and Young s modulus of the tip and v and are the Poisson s ratio and Young s modulus of the sample We assume that the tip modulus E is much larger than the
28. d reduced modulus E Refer to Calibrate Peak Force QNM Section 4 6 f or details Rev F PeakForce QNM 29 PeakForce QNM Operation PeakForce QNM Parameters 2 6 4 PeakForce QNM Limits These parameters work like other limits in the NanoScope software Numbers in the NanoScope software are represented using 16 bits and thus various quantities are represented as illustrated in Figure 2 6c Figure 2 6c Illustration of PeakForce QNM Limits DSP Computer 32767 Force Dissipation DMT Modulus Limit 2 Force Dissipation or DMT Modulus Limit 2 As with other limits setting the limit too high increases the bit noise Setting the limit too low can result in wrapped data and inverted contrast The limits of the following parameters can be set by the user e Force Limit affects the Peak Force and Adhesion channels e Dissipation Limit affects the Dissipation channel DMT Modulus Limit affects the DMT Modulus channel LogDMT Modulus Limit affects the LogDMT Modulus channel LogDMT Modulus Offset affects the LogDMT Modulus channel 30 PeakForce QNM Rev F PeakForce QNM Operation PeakForce QNM Parameters 2 6 5 Limits Parameters Z Limit Permits attenuation of maximum allowable Z voltage and vertical scan range to achieve higher resolution smaller quantization in the Z direction Range or Settings Dimension Icon 8 33 V 0 241 to 309 3 V 9 um e Mult
29. e for each range is indicated as well HOPG SILICA DNISP HS E PS A 525 HPDE PP RTESPA LDPE TAP150A Rubber PDMS e SNL A 100E 3 1E 6 10E 6 100E 6 1E 9 10E 9 100E 9 Young s Modulus Pa Table 4 2a Legend Symbol Chemical Name PDMS Polydimethylsiloxane LPDE Low density polyethylene HPDE High density polyethylene PP Polypropylene PS Polystyrene HOPG Highly Oriented Pyrolytic Graphite 54 PeakForce QNM Rev F Calibration Absolute vs Relative Calibration Methods 4 2 1 The Relative Method The relative method of calibration uses a sample of known modulus to obtain the ratio of spring constant to the square root of tip end radius It is still important to accurately calibrate the deflection sensitivity in order to obtain modulus results An outline of the procedure follows 1 Calibrate the Deflection Sensitivity on a clean hard sample Sapphire or Silicon which can be used for samples with modulus less than 10 GPa See Calibrate the Deflection Sensitivity Section 4 3 for a procedure to measure this 2 If quantitative Adhesion or Dissipation data is required use the NanoScope Thermal Tune function to obtain the spring constant otherwise enter the nominal value from the manufacturer See Calibrate the Spring Constant Using Thermal Tuning Section 4 4 for a procedure to measure this 3 Image the reference sample using PeakForce QNM a
30. e reg 18 2 5 5 Dissipatiori 2 23 e 4 LEe ag edd mda vec ev a led EXE NAR RE 20 2 5 6 Deformation Hass svete e SU eS PIS Ne ER EN IE 22 2 6 PeakForce QNM 23 2 6 1 Ses 23 2 6 2 PeakForce QNM Control 26 2 6 3 Cantilever Parameters cv ec 665s ees ve ETE Fh e re oh a 29 Rev F PeakForce QNM iii Chapter 3 Chapter 4 Chapter 5 2 6 4 PeakForce QNM Limits cece cece cee cee ehe Hh eee ees 30 2 6 5 Limits Parameters s 88 te A IUS HERI RUN 31 2 6 6 Other Parameters sva voe ve s c rh eR RR ERR e Re alee RC UR 32 2 67 Parameter Visibility cus etae raa ere 34 2 7 Capture Buttonsz s o SS T MES 36 2 8 Optimizing a ScanAsyst 38 2 9 Advanced Atomic Force Operation 40 2 9 Displaying Parameters moe aria fee esos ete RR RUE 40 PeakForce QNM Samples 47 3 PDMS S0 ft Ti o sys dee dosed rem reote PERDU Ode Kor 48 32 PDMS Softe2 seis fs ie Pensa hh y err Per ERE GU es ee eis PE ETE RS 49 3 37 Polystyrene quercu e vf b eb E 50 RE loo ei Go tee eae ioe twee eee ead 51 BD F
31. e sample based on the DMT model 16 PeakForce QNM Rev F PeakForce QNM Operation PeakForce QNM Channels 2 5 3 Adhesion The peak force below the baseline shown in Figure 2 5c Figure 2 5d shows an adhesion map of a Rev F PS LPDE blend Figure 2 5 Adhesion on a PS LDPE blend Adhesion 10 20 30 CENE 60 70 80 Figure 2 5d Adhesion map of a PS LDPE blend s OF a n PeakForce QNM 17 PeakForce QNM Operation PeakForce QNM Channels 2 5 4 Peak Force This channel produces a map of the peak force see Figure 2 5g measured during the scan Because the PeakForce QNM mode uses peak force as the feedback signal this channel is essentially the Peak Force Setpoint plus the error Figure 2 5e and Figure 2 5f illustrate the peak force location Figure 2 5e The heartbeat Force vs Time 10 Peak 5 Ia D 2 o 5 50 100 150 200 250 300 350 400 450 Time ps Figure 2 5f Force curve Force vs distance 10 i Peak Force 0 e o 5 50 100 150 200 250 300 Z nm 18 PeakForce QNM Rev F PeakForce QNM Operation PeakForce QNM Channels Figure 2 5g Peak Force Error map of a PS LDPE blend i nia Ei Rev F PeakForce QNM 19 PeakForce QNM Operation PeakForce QNM Channels 2 5 5 Dissipation Energy Dissipation W is given by the force times the velocity integrated over one period of the vibration
32. ep found in Microscope gt Engage Settings gt General shown in Figure 2 6d Range or Settings Dimension Icon 0 001 V 1 229 V Default value 0 15 V e MultiMode 8 0 001 V 1 229 V Default value 0 15 V BioScope Catalyst 0 001 V 1 229 V Default value 0 3 V Figure 2 6d SPM engage step Engage Settings General Stage Sew tip Yes v SPM safety 50 0 um Sewing trigger 7 SPM engage step 0 332 um Trigger safety SPM withdraw 100 Pre engage setpoint Engage Setpoint Tapping Delta Setpoint 0 0600 Final Delta Setpoint 0 0600 Test threshold slope 25 0 Test threshold dZ Engage min setpt 7 25 TM engage gain 1 00 32 PeakForce QNM Rev F PeakForce QNM Operation PeakForce QNM Parameters Medium The medium surrounding the sample and probe This parameter is selected when you select either PeakForce QNM in Air Range and Settings AIR FLUID SHOW ALL discussed in the NanoScope Software Version 8 User Guide must Note be enabled to view and edit this parameter 33 Rev F PeakForce QNM PeakForce QNM Operation PeakForce QNM Parameters 2 6 7 Parameter Visibility The visibility of various parameters depends on the selected mode Table 2 6a shows parameter visibility as a function of microscope mode Table 2 6a Parameter Visibility Panel Parameter Simple Mode E
33. es and then open the FrcExport files Details can be found in the Line Plot and Multiple Line Plot page of the Force Curve and Ramping Analysis in the help pages of the NanoScope Analysis package 54 PeakForce QNM Input Parameters The parameters appearing in the PeakForce QNM Input Parameters window have been collected in real time but may be modified for off line analysis here Deformation Sensitivity Deflection Sensitivity Spring Constant e Hsdc Display Channel 5 5 Exported Force Curves Exported force curves file names begin with FrcExport can be viewed in NanoScope software or NanoScope Analysis software Off line plots feature more display options for exported curves than are available for HSDC files These additional options are listed below 76 PeakForce QNM Rev F Offline Analysis Exported Force Curves 5 5 1 Time Domain Plots Change the X Data Type from Z HEIGHT to TIME to transform the original force curve shown in Figure 5 5a to a Force vs Time plot a k a heartbeat shown in Figure 5 5b Figure 5 5a Exported force curve Une Piot 1000 ton ipm PeakF PeakForce QNM 7T Rev F Offline Analysis Exported Force Curves Figure 5 5b Force vs time Une Plot 1000 PeakF Deflection pra Sensitivity 5 5 2 Plot Units D ota type LB The Y axis can be displayed as VOLTS Deflection METRIC distance in nano me
34. es are supplied with the PeakForce QNM kit Note All samples are homogeneous and glued to Bruker sample pucks Note Probe or sample contamination may compromise the accuracy of the quantitive measurements Rev F PeakForce QNM 47 PeakForce QNM Samples PDMS Soft 1 3 1 PDMS Soft 1 Nominal modulus 2 5 MPa This 150 um thick PDMS gel sample is formulated for long shelf life and stability Suggested probe ScanAsyst Air A typical force curve of this sample is shown in Figure 3 1a and an image of the modulus is shown in Figure 3 1b The standard deviation of the modulus in this image is 0 7 MPa Figure 3 1a Typical force curve of a PDMS Soft 1 sample Hi Force nN 150 Z nm Figure 3 1b Typical modulus image of a PDMS Soft 1 sample e SQ a 35MPs 1 00 3 OMTModaus 00 48 QNM Rev F PeakForce QNM Samples PDMS Soft 2 3 2 PDMS Soft 2 Nominal modulus 3 5 MPa This 150 um thick PDMS gel sample is formulated for long shelf life and stability Suggested probe ScanAsyst Air A typical force curve of this sample is shown in Figure 3 2a and an image of the modulus is shown in Figure 3 2b The standard deviation of the modulus in this image is 0 5 MPa Figure 3 2a Typical force curve of a PDMS Soft 2 sample 0 5 0 AJ B WC T di T proT 05 A 250 200 Force nN 150 Z nm Figure 3 2b Typical modulus image of a
35. force curve at every pixel in the image The peak interaction force of each of these force curves is then used as the imaging feedback signal Peak Force Tapping mode modulates the Z piezo at 2 kHz Icon MultiMode Catalyst operates at 1 kHz with a default Peak Force Amplitude of 150 nm 0 peak Analysis of force curve data is done on the fly providing a map of multiple mechanical properties that has the same resolution as the height image Rev F PeakForce QNM PeakForce QNM Operation PeakForce QNM Principles of Operation 2 2 2 The Heartbeat The Force vs Time display shown in Figure 2 2a is referred to as the heartbeat The initial contact of the probe with the sample B peak force C and adhesion D points are labelled Figure 2 2a The heartbeat Blue indicates approach while red indicates retract B approach pv withdraw 2 2 3 Force curves Using the Z position information the heartbeat is transformed into a force curve shown in Figure 2 2b The force curve plot is analyzed on the fly to produce the peak interaction force as the control feedback signal and the mechanical properties of the sample Adhesion Modulus Deformation Dissipation Figure 2 2b Force curve Rev F PeakForce QNM PeakForce QNM Operation PeakForce QNM Probe Selection 2 3 PeakForce QNM Probe Selection Itis important to choose a probe that can cause enough deformation of the sample and still retain
36. he Scan Parameter List for PeakForce QNM in 40 Figure 2 9b The EXPANDED MODE view of the Scan Parameter List for ScanAsyst in Air cee eee eee ee eee eee 41 Figure 2 9c The Configure Experiment information window 42 Figure 2 94 The Configure Experiment Window 42 Figure 2 9e Select SHOW ALL items 43 Figute 2 9f Enable Parameters 4 429 4 9o tate tt ete seit 44 Chapter 3 PeakForce QNM Samples 47 Figure 3 1a Typical force curve of a PDMS Soft 1 sample 48 Figure 3 1b Typical modulus image of a PDMS Soft 1 sample 48 Figure 3 2a Typical force curve of a PDMS Soft 2 sample 49 Figure 3 2b Typical modulus image of a PDMS Soft 2 sample 49 Figure 3 3a Typical force curve of a Polystyrene sample 50 Figure 3 3b Typical modulus image of a Polystyrene sample 50 Figure 3 4a Typical force curve ofa HOPG 51 Figure 3 4b Typical modulus image of a HOPG sample 51 Chapter 4 Calibration ccce ei eae ERE UR RR RR 53 Figure 4 2a Modulus ranges covered by various probes The modulus of the reference sample for each range is indicated as well 54 Figure 4 3a The PeakForce QNM in Air Select Experiment window 56 Figure 4 3b Force Curve Cursors eee 58 Figure 4 3c Deflectio
37. iMode 8 11 V 0 1375 um to 416 V 5 e BioScope Catalyst 1 V 0 1252 um to 145 V 18 um Note SHOW ALL discussed in the NanoScope Software Version 8 User Guide must be enabled to view and edit this parameter Z Range Permits attenuation of the range of the Z piezo as measured by the Z sensor to achieve higher resolution smaller quantization in the Z direction Range or Settings e Dimension Icon 0 2 nm to 10 microns BioScope Catalyst 0 2 nm to 28 microns Note The Z Range parameter does not apply to the MultiMode because it does not incorporate a Z sensor Deflection Limit Use this parameter to attenuate the maximum allowable deflection signal to achieve higher resolution If this value is too small saturation of the Deflection channel will occur Range or Settings 4 096V 24 58V Rev F PeakForce QNM 31 PeakForce QNM Operation PeakForce QNM Parameters 2 6 6 Other Parameters Peak Force Engage Setpoint Laser interference from reflective samples can cause a false engage which can be avoided by using a large Peak Force Engage Setpoint This is why a relatively large and conservative Peak Force Engage Setpoint default value is used But large Peak Force Engage Setpoints can damage samples and probes particularly cantilevers with high spring constants To reduce the engage force reduce the Peak Force Engage Setpoint When you reduce Peak Force Engage Setpoint you should also reduce SPM engage st
38. igger Delay Upload Slope Positive Delay 512 ms Duration 1536 ms Status Failed 4 Click the UPLOAD DATA button to transfer the captured data to the computer While the data transfer process takes place the scan data will look corrupted because the DSP time is shared between PeakForce QNM properties computation and data transfer Rev F PeakForce QNM 37 PeakForce QNM Operation Optimizing a ScanAsyst Image 2 8 Optimizing a ScanAsyst Image When the relative Z position between the probe and sample is modulated parasitic cantilever motions occur These motions include free cantilever oscillation after snapping off the surface deflection triggered by harmonics of the piezo motion or viscous forces This parasitic deflection defined as the deflection signal variation when the tip is NOT interacting with the sample limits the low force range of ScanAsyst operation Low force control is the most important factor to achieve high resolution imaging and property measurements During peak force tapping operation the Auto Config operation is used to analyze the parasitic deflection signal including its data pattern by comparing the known source of parasitic excitation namely the cantilever resonance at pulling off modulation harmonics and other system actuation sources The signature of the interaction in the shape of heartbeat signal is extracted from the parasitic deflections The recovered heartbeat signal bec
39. imension Dimension Icon BioScope BioScope Catalyst Atomic Force Profiler AFP Dektak Software Modes TappingMode Tapping TappingMode LiftMode AutoTune TurboScan Fast HSG PhaseImaging DekMap 2 HyperScan StepFinder SoftScan ScanAsyst Peak Force Tapping PeakForce QNM Hardware Designs TrakScan StiffStage Hardware Options TipX Signal Access Module and SAM Extender TipView Interleave LookAhead Quadrex Software Options NanoScript Navigator FeatureFind Miscellaneous NanoProbe Cover Image Anti bacterial film consisting of poly methyl methacrylate and silver nanoparticles The sample was imaged on a Dimension Icon using PeakForce QNM at a scan size of 13 5 um The data shown is adhesion data overlaid on topography The dark red spots correspond to the location of silver nanoparticles which are difficult to identify using topography alone Sample courtesy of Mishae Khan and Daniel Bubb Rut gers University Table of Contents List of FiQures tese Se tate aie eee TE vii Chapter 1 Introduction to PeakForce QNM Microscopy 1 FT Introduction c ene rcr 1 1 2 What is in the PeakForce QNM kit 2 1 3 Conventions and 2 Chapter 2 PeakForce QNM Operation
40. ings 0 5 nm is appropriate for most samples while nm is appropriate for rough samples and 0 05 nm may be appropriate for very flat samples Note When ScanAsyst Auto Z Limit control is turned ON the ScanAsyst Noise Threshold parameter is automatically set by the program and cannot be changed 24 PeakForce QNM Rev F PeakForce QNM Operation PeakForce QNM Parameters ScanAsyst Auto Config Frames At the end of every N frames an AUTO CONFIG operation is performed Range and Settings 0 100 If ScanAsyst Auto Config Frames 0 periodic AUTO CONFIG operations are not performed ScanAsyst Auto Control Range and Settings OFF Turns ScanAsyst Auto Control OFF On Turns ScanAsyst Auto Control ON INDIVIDUAL Allows individual control of ScanAsyst Auto Gain ScanAsyst Auto Setpoint ScanAsyst Auto Scan Rate and ScanAsyst Auto Z Limit ScanAsyst Auto Gain ScanAsyst Auto Gain allows NanoScope to dynamically control Feedback Gain Range and Settings OFF Turns ScanAsyst Auto Gain OFF On Turns ScanAsyst Auto Gain ON ScanAsyst Auto Setpoint ScanAsyst Auto Setpoint allows NanoScope to dynamically control the Peak Force Setpoint Range and Settings OFF Turns ScanAsyst Auto Setpoint OFF On Turns ScanAsyst Auto Setpoint ON Note This option is very useful for users who want to change the Peak Force Setpoint manually to achieve adequate deformation on the sample while leaving ScanAsyst Auto Gain ON ScanAsyst Scan Auto Scan Rate Sca
41. ion will be slightly larger than the displayed deformation because the default Deformation Fit Region is 85 of the full deformation See Deformation Fit Region Page 28 Figure 2 5j Deformation Deformation Fit Region Force nN 10 20 30 40 50 60 70 80 lal Separation nm 22 PeakForce QNM Rev F PeakForce QNM Operation PeakForce QNM Parameters Figure 2 5k Deformation map of a PS LDPE blend 26 PeakForce QNM Parameters 2 6 1 Feedback Parameters Peak Force Setpoint The setpoint for peak force If the deflection sensitivity is calibrated the force in Newtons will be displayed When the ScanAsyst Setup is ON Peak Force Setpoint is automatically controlled by NanoScope software Under some conditions you may desire to control the Peak Force Setpoint manually A Peak Force Setpoint that is too high can either damage the sample or wear the tip It is generally desirable to reduce the Peak Force Setpoint to as small a value as is possible However in order to achieve accurate Elastic modulus measurement sufficient sample deformation is needed If the deformation is less than 2nm increase the Peak Force Setpoint to achieve sufficient sample deformation Note When performing AUTO CONFIG operations with a small Peak Force Setpoint less than 20mV the tip may drift out of contact with the surface and will be unable to return and track the surface It is therefore recommended using a rel
42. l and will merely add a small amount of noise to the feedback Rev F PeakForce QNM 13 PeakForce QNM Operation Basic PeakForce QNM Operation 4 The HEIGHT channel in the Scan window shown in Figure 2 4h will display topographical image of your sample Figure 2 4h Height Image of a PS LPDE blend e Sim 14 PeakForce QNM Rev F PeakForce QNM Operation PeakForce QNM Channels 25 PeakForce QNM Channels This section discusses channels that are specific to PeakForce QNM mode Mechanical properties can be extracted from the calibrated see Chapter 4 force curves 2 5 1 DMT Modulus The reduced Young s Modulus is obtained by fitting the retract curve green line in Figure 2 5a using the Derjaguin Muller Toropov DMT model given by _ 40 3 3E Rd F yay Where F is the force on the tip Faan is the adhesion force R is the tip end radius and d is the tip sample separation Figure 2 5a Force vs Separation plot DMT modulus fit region 20 40 60 80 100 Separation nm 1 Derjaguin B V Muller V M Toropov Yu P J Colloid Interface Sci 53 314 1975 Rev F PeakForce QNM 15 PeakForce QNM Operation PeakForce QNM Channels Figure 2 5b shows a DMT Modulus map of PS LDPE blend Figure 2 5b DMT Modulus map of a PS LDPE blend T9 ci 2 5 2 Log DMT Modulus The logarithm of the elastic modulus of th
43. lays all the force curves between the vertical cursors The location of the force curves can be controlled by dragging either the dashed blue cursors in the image the dashed red cursors see Step 7 on Page 73 in the time display or entering the numbers in the Force Curve Selection panel See Figure 5 3b Figure 5 3b Multiple Force Curve Selection Deflection Eror m 40 LJ 100 2 40 160 199 1 Image Une Selection gt 12 arere Forca Curve Seon Cpu s 5 Restore Del Both 168 nm V 24 5 21 50 N m PS LDPESO film 014 1 00 LogDMTModuus 40pm Rev F PeakForce QNM 75 Offline Analysis PeakForce QNM Input Parameters 5 3 3 Force Curve Type Range and Settings BOTH Display both the extend and retract portions of the Z piezo ramp TRACE Displays the extend portion of the Z piezo ramp RETRACE Displays the retract portion of the Z piezo ramp 5 3 4 Exporting Force Curves Click the EXPORT CURVES button to export either a PAIR of force curves or MULTIPLE curves in a directory FrcExport One file will be created for each force curve This binary file header is ASCII can be opened by the NanoScope Analysis package Because off line plots either NanoScope or NanoScope Analysis feature more display options for exported curves FrcExport than HSDC files you may wish to export your curv
44. lbar A pre engage check begins followed by Z stage motor motion 2 To move to another area of the sample execute a Withdraw command to avoid damaging the tip and scanner 2 4 9 Image the sample 1 If needed right click in the Force Monitor window and click UNDOCK See Figure 2 4f You may DOCK the undocked Force Monitor window by right clicking in it and clicking DOCK Figure 2 41 Undock the Force Monitor window 50 Auto Config 40 Switch Display Type 30 Display Options UnDock 20 Force pv 50 100 150 200 250 Z nm 12 PeakForce QNM Rev F PeakForce QNM Operation Basic PeakForce QNM Operation Select one plot to be FORCE vs TIME and the other to be FORCE VS Z Once scanning the Force Monitor window shown in Figure 2 4g should display a Force vs Z plot and a heartbeat Force vs Time plot gt o o nm Display Type Data Scale Force nN Display Type Data Scale Figure 2 4g Force Monitor window Force 2 Auto Scale Force vs Time v Auto Scale Note The cantilever oscillation after it snaps off the sample surface shown in Figure 2 4g is normal On occasion this oscillation will continue until the probe tip again contacts the sample surface This oscillation will be heavily damped by this contact Even if the oscillation is not fully damped the remaining oscillation at the force peak will be smal
45. ment Category Scan Asyst lt ScanAsyst Tapping Contact Mode Mode TY Wt Electrical amp Mechanical Other SPM Magnetic Properties Select Experiment Group Force Moduluation Force Volume Nanoindentation Quantitative Nanomechanical Mapping Select Experiment Harmonix PeakForce in Air PeakForce QNM in Fluid Select Experiment Dimension Icon t3 Microscope Dimension Icon gt gt Change Microscope Setup Experiment Description PeakForce is a groundbreaking atomic force microscope AFM imaging mode that provides AFM researchers unprecedented capability to quantitatively characterize nanoscale materials It maps and distinguishes between nanomechanical properties including modulus and adhesion while simultaneously imaging sample topography at high resolution PeakForce QNM operates over an extremely wide range approximately 1 MPa to 50 GPa for modulus and 10 to 10 UN for adhesion enabling characterization of a large variety of sample types Because it s based on Veeco s new proprietary Peak Force Tapping technology the forces applied to the sample are precisely controlled and a variety of probes can be used This allows m Load Experiment 2 Select MECHANICAL PROPERTIES in the Experiment Category panel 3 Select QUANTITIVE NANOMECHANICAL MAPPING in the Select Experiment Group panel 56 PeakForce
46. n Sensitivity Dialogue 58 Figure 4 4a Select Thermal Tune Frequency Range 59 Figure 4 4b The Thermal Tune 1 60 Figure 4 4c Median Filter Width eee 61 Figure 4 44 Spring Constant Calculation Result 62 Figure 4 5a Plane Fit of the Characterizer 63 Figure 4 5b Typical force curve of a PDMS Soft 1 sample Nominal modulus 2 5 64 Figure 4 5c Tip Qualification 65 Figure 4 6a The Cantilever Parameters panel 66 Chapter 5 Offline 5 69 Figure 5 2 The QNM Hsdc Force Curve Image window 70 Figure 5 2b The HEIGHT channel of the image 71 Figure 5 2c Vertical cursors display X position 72 Figure 5 24 The QNM Hsdc Force Curve Image window 73 Figure 5 3a PeakForce QNM 74 viii PeakForce QNM Rev F List of Figures Figure 5 3b Multiple Force Curve 75 Figure 5 5a Exported force 77 Figure OD ocd dea dod dan 78 Figure 5 5c Force vs separation cece eee nnn 79 Figure 5 6a Young s modulus in a m
47. nAsyst Scan Auto Scan Rate allows NanoScope to control the Scan Rate Range and Settings OFF Turns ScanAsyst Scan Auto Scan Rate OFF ON Turns ScanAsyst Scan Auto Scan Rate ON Rev F PeakForce QNM 25 PeakForce QNM Operation PeakForce QNM Parameters ScanAsyst Auto Z Limit ScanAsyst Auto Z Limit allows NanoScope to control the Z Limit The ScanAsyst Auto Z Limit function will detect if the surface is sufficiently smooth to allow reduction of the Z Limit and thus avoid bit noise in the Height and Height Sensor channel This will be effective after a whole frame of the image is scanned If the Z Limit needs to be reduced the ScanAsyst Noise Threshold will automatically be reduced to 0 15 times the original ScanAsyst Noise Threshold to reduce the oscillation noise for smooth samples Range and Settings OFF Turns ScanAsyst Auto Z Limit OFF On Turns ScanAsyst Auto Z Limit ON 2 6 2 PeakForce QNM Control Parameters Peak Force Amplitude The zero to peak amplitude of the cantilever drive in the Z axis Z modulation Increasing Peak Force Amplitude will reduce the contact time during each tip tapping cycle on the sample and help tracking the rough and or sticky sample by avoiding a situation where the tip is unable to pull off from the sample Reduced Peak Force Amplitude is desired in liquid on flat samples Less Peak Force Amplitude results in less hydrodynamic force disturbance Lift Height The distance that the Z piezo i
48. nd adjust the Tip Radius parameter to make the measured Modulus equal the known value of the reference sample 4 Image the unknown sample adjusting the Peak Force Setpoint to match the deformation depth used during imaging of the reference sample 4 2 2 The Absolute Method The absolute procedure is very similar to the relative procedure except for two important differences 1 The spring constant calibration Step 2 is not optional 2 Instead of using the reference sample the tip end radius is measured by scanning a tip calibration artifact such as TipCheck Bruker part RS and analyzing the resulting image See Measure the Tip Radius Section 4 5 for a procedure to measure this Note The absolute procedure has the benefit that there is no concern over the accuracy of the modulus of the reference sample or whether it ages over time or becomes contaminated Rev F PeakForce QNM 55 Calibration Calibrate the Deflection Sensitivity amp 4 3 Calibrate the Deflection Sensitivity Because Peak Force QNM mode ramps the Z piezo and acquires force curves measuring deflection sensitivity requires fewer steps than the normal ramp procedure 1 Click the SELECT EXPERIMENT icon This opens the Select Experiment window shown in Figure 4 3a Figure 4 3a The PeakForce QNM in Air Select Experiment window Select From Oo Use previous experiment PeakForce QNM in Air 11 27 09 22 05 Or Choose an Experi
49. o AAA AREIS 76 5 5 1 Time Domain Plots nassen e ry Ry heh Gio 77 5 52 Plot WAM tase ee ee costs eset sir uy eR e dne 78 5 5 3 Display Mode accedi A eek Re bs 79 PeakForce QNM Rev F Rev F PeakForce QNM vi PeakForce QNM Rev F List of Figures Chapter ii List of Figures eae eem Ire eee vii Chapter 1 Introduction to PeakForce QNM Microscopy 1 Chapter 2 PeakForce QNM Operation 3 Figure 2 2a The heartbeat Blue indicates approach while red indicates retract c i o V PR Ver EINE 4 Figure 2 20 Force cutye scoc 2s biens estela ad npe a RE orgs 4 Figure 2 4a Mode selector switch 6 Figure 2 4b The PeakForce QNM in Air Select Experiment window 7 Figure 2 4c PeakForce QNM in Air Simple Mode configuration 8 Figure 2 4d PeakForce QNM in Air SIMPLE MODE Parameters Panel cece cece eee ee eee eee 10 Figure 2 4e Suggested PeakForce QNM Channel Settings 11 Figure 2 4f Undock the Force Monitor window 12 Figure 2 4g Force Monitor 13 Figure 2 4h Height Image ofa PS LPDE 14 Figure 2 5a Force vs Separation plot 15 Figure 2 55 DMT Modulus map of a PS LDPE
50. omes the interaction force curve plotted in the time domain Figure 2 8a shows the heartbeat and force vs Z curves of an image before and after AUTO CONFIG correction The low frequency noise in the baseline has been removed Figure 2 8a The heartbeat and force curves of an image before left and after right AUTO CONFIG correction amp PeakForce QNM in Air Force Monitor PeakForce QNM in Air Force Monitor Jog MEAR Force nN 15 1 o i Force nN pm b in 50 100 150 200 250 50 100 150 200 250 Data Scale Auto Scale Stop Auto Config Update Sens Capture Lin Auto Config Update Sens Capture Line Z nm Z nm Display Type Force vsZ v Display Type Force vs Z x Data Scale Auto Scale Data Scale Auto Scale 15 15 1 05 05 z 0 8 z S 05 05 4 45 3 50 100 150 200 250 300 350 400 450 50 100 150 200 _ 250 300 350 400 450 Time us Time ys Display Type Force vs Time v Display Type Force vs Time 1 Data Scale Auto Scale 38 PeakForce QNM Rev F PeakForce QNM Operation Optimizing a ScanAsyst Image If your force vs time curves show parasitic background noise or the force vs height curve load and unload curves are overlapping due to background noise click the AUTO CONFIG button shown in Figure 2 8b to invoke the real time pattern analysi
51. possible However in order to achieve accurate Elastic modulus measurement sufficient sample deformation is needed If the deformation is less than 2nm increase the Peak Force Setpoint to achieve sufficient sample deformation 66 PeakForce QNM Rev F Calibration Calibrate Peak Force QNM For the relative method you should adjust the Peak Force Setpoint to keep the Deformation the same for both the reference and measurement samples Feedback Gain Reduce the Feedback Gain to lower the noise in the property channels If ScanAsyst Auto Gain is On set the ScanAsyst Noise Threshold to 0 5nm or less Rev F PeakForce QNM 67 Calibration Calibrate Peak Force QNM 68 PeakForce QNM Rev F NanoScope Analysis Chapter5 Offline Analysis 5 1 5 2 Introduction As discussed in Chapter 2 real time PeakForce QNM saves images of processed data like modulus and adhesion There are times when one would like to compare these processed data images with the associated force curves For this reason a PeakForce QNM mode off line analysis function is included in the NanoScope Analysis package The main intention of this function is to allow you to view and analyze force curves from areas where material properties are most likely to change You are given options to export raw force curves that can then be analyzed in the NanoScope Analysis or third party analysis programs As discussed in Section 2 7 you should
52. rb Withdraw 329m L mom fg 20 mom Orr ton fede 02000V AT Planet Dua Type hegi Sess Renace Canter Orem OL Pure ft ore Pes Force w Contr OL Pure Pi None v Force Monitor Window Pek ee ee Orel 3 Son AT Pure fi Orr 5 Sce AT Awe Pt Oat Tie Race w Cete oae Aden v Certe OV Ch Pare Ft Tons On Surface Opis Tum 2 4 4 Head Cantilever and Sample Preparation 1 Install a suitable probe onto an AFM cantilever holder See PeakForce QNM Probe Selection Section 2 3 2 Load the cantilever holder with installed tip into your microscope 8 PeakForce QNM Rev F PeakForce QNM Operation Basic PeakForce QNM Operation 2 4 5 Align Laser 1 Align the laser using the laser control knobs Note Coated cantilevers are strongly recommended to increase the laser sum signal and decrease interference effects Note Maximize the laser sum signal to avoid optical interference Note Try not to change the laser spot position during the experiment This may change the Deflection Sensitivity and therefore the property measurements 2 4 6 Adjust Photodetector 1 Adjust the photodetector Rev F PeakForce QNM 9 PeakForce QNM Oper
53. rmation Sens 168 nmv Deflection Sens 24 5 Spring Constant 21 50 Nim Display Channel 1 Rotrace image from PS LOPESO film 014 Rev F PeakForce QNM 73 Offline Analysis Controls and Settings 5 3 Controls and Settings 5 3 1 Image Line Selection Range and Settings ALL Displays all captured lines ONE LINE Displays one captured scan line of taps The arrow in the Image Line Selection panel and the solid blue line shown in Figure 5 2b display the scan direction The counters are displayed in the Force Curve Selection panel Figure 5 PeakForce QNM Controls pray Sep L_toadimase _ Load Image Image C Al OneLine 0 gt Force Curve Selection Export Curves Pair Multiple 461 462 Restore Default E PeakForceQNM Input Parameters Force Curve Type Both Deformation Sens 172 nm V Deflection Sens 45 0 nm V Spring Constant 33 33 N m Hsdc Display Channel 1 L Retrace image from tesp ps Idpesp 001 74 PeakForce QNM Rev F Offline Analysis Controls and Settings 5 3 2 Force Curve Selection Range and Settings PAIR Displays a pair of force curves See Figure 5 2d for an example The location of the pair of force curves can be controlled by moving either the dashed blue cursors in the image the dashed red cursors see Step 7 on Page 73 in the time display or entering the numbers in the Force Curve Selection panel MULTIPLE Disp
54. rve Cursors Channel 1 Data Type Deflection Erro Data Scale 62 35 nm S o E a X Data Type 2 z 12 Click the UPDATE SENSITIVITY icon in the NanoScope toolbar or select Ramp gt Update Sensitivity The software will automatically calculate the deflection sensitivity and open the Set Realtime Channel Sensitivities window see Figure 4 3c Figure 4 3c Deflection Sensitivity Dialogue Box Set Realtime Channel Sensitivities The measured Deflection Error sensitivity 24 55 nm Deflection Sensitivity amp TM Deflection Error Sens need for thermaltune Deflection Sens Amplitude Error Sens Amplitude Sens Click OK to update the sensitivities of checked types It starts to affect next live curve Cancel 13 Click OK to accept this deflection sensitivity in the dialogue box that displays and it will automatically be entered into the Deflection Sensitivity parameter 58 PeakForce QNM Rev F be Calibration Calibrate the Spring Constant Using Thermal Tuning 44 Calibrate the Spring Constant Using Thermal Tuning Note Bruker recommends Thermal Tune included in NanoScope software for probes with spring constants less than or equal to 1 N m Other methods Sader added mass vibrometer pre calibrated probes are recommended for probes with higher spring constants These techniques are reviewed in detail in Bruker Application Note 9
55. s The capture buttons in the Force Monitor window allow you to collect data for use with the NanoScope Analysis off line analysis software 1 Start to collect a ScanAsyst Peak Force Tapping image 2 When you are in a region of interest click the CAPTURE LINE button shown in Figure 2 7a to capture a scan line Figure 2 7a CAPTURE LINE button ScanAsyst in Air Force Monitor m 1 Display Type Force vsZ Data Scale Auto Scale Display Type Force vs Time Data Scale Auto Scale Le Jine ee 36 PeakForce QNM Rev F PeakForce QNM Operation Capture Buttons 3 The High Speed Data Capture window shown in Figure 2 7b will open and the Status will change when the data has been captured UPLOAD DATA to the PC when the capture is complete When CAPTURE LINE is used this way the off line NanoScope Analysis software will correctly associate the capture line of the high speed data capture with the line in the image Figure 2 7b High speed data capture is complete However the data is not immediately transferred to the PC High Speed Data Capture Channel Selection Channel4 Data Type Off Rate szsms v NS ChannelB Data Type Off z x ChannelC Data Type Deflection Error v ChannelD Data Type Height v Rate 500 kHz Trigger Controls Event EOL Arm Trigger Cl uto Re Arm Channel Height Level 0 00 V Force Tr
56. s algorithm that removes parasitic deflection Note Clicking AUTO CONFIG will automatically calculate the Lift Height and perform an AUTO CONFIG operation Figure 2 8b The AUTO CONFIG button 5 Scandsyst in Air Force Monitor oN Display Type Force vsZ Data Scale Auto Scale Display Type Force vs Time Data Scale Auto Scale Rev F PeakForce QNM 39 PeakForce QNM Operation Advanced Atomic Force Operation Note When performing AUTO CONFIG operations with a small Peak Force Setpoint less than 20mV the tip may drift out of contact with the surface and will be unable to return and track the surface It is therefore recommended using a relatively large Peak Force Setpoint while performing AUTO CONFIG operations and reducing the Peak Force Setpoint later if necessary 2 9 Advanced Atomic Force Operation 2 9 1 Displaying Parameters You can adjust the number of parameters shown in the Scan Parameter List using several methods Simple Mode 1 The default SIMPLE MODE intended for novice users and shown in Figure 2 9a displays the minimum number of parameters needed to make an image Figure 2 9a The SIMPLE MODE view of the Scan Parameter List for PeakForce QNM in Air B Scan Scan Size 500 nm Aspect Ratio 1 00 I X Offset 0 000 nm Y Offset 0 000 nm Scan Angle 0 00 9 Scan Rate 0 977 Hz L samples Line 512 B Feedback Peak Force Setpoint 0 1000 V
57. s retracted from the sample during an AUTO CONFIG operation Note Changing the Lift Height will automatically start the AUTO CONFIG function see Optimizing a ScanAsyst Image Page 38 and retract the Z piezo to the specified Lift Height Clicking AUTO CONFIG will automatically calculate the Lift Height and perform an AUTO CONFIG operation 26 PeakForce QNM Rev F PeakForce QNM Operation PeakForce QNM Parameters Top Fit Region The Top Fit Region of the unload force curve shown in Figure 2 6a is excluded from the DMT Modulus calculations Note smaller Top Fit Region means that less region of the force curve is excluded from the DMT modulus calculations Range and Settings 0 94 Typical 10 Figure 2 6a DMT Fit regions of the Force curve Unload Fit Region Force nN 10090 10 20 30 40 50 60 70 80 Separation nm Unload Fit Region The Unload Fit Region of the force curve shown in Figure 2 6a is included in the DMT Modulus calculations Range and Settings 0 100 100 is defined as the force between the adhesion point and the peak force Typical 70 The portion of the force curve between the Top Fit Region and the Unload Fit Region is included in the DMT Modulus calculations For typical numbers discussed here the region between 10 and 70 of the unload force curve will be included in the DMT modulus calculations Rev F PeakForce QNM 27 PeakForce
58. terization of a large variety of sample in Air types PeakForce QNM in Fluid Experiment Description Because it s based on Veeco s new proprietary Peak Force Tapping technology the forces applied to the sample are precisely controlled and a variety of probes can be used This allows Load Experiment 2 Select MECHANICAL PROPERTIES in the Experiment Category panel 3 Select QUANTITIVE NANOMECHANICAL MAPPING in the Select Experiment Group panel 4 Select PEAKFORCE QNM IN AIR in the Select Experiment panel and click LOAD EXPERIMENT Rev F PeakForce QNM 7 PeakForce QNM Operation Basic PeakForce QNM Operation 5 This opens the Workflow Toolbar the Scan 4 Channels Icon windows the Force Monitor window and the Scan Parameters List window shown in Figure 2 4c Figure 2 4 PeakForce QNM in Air Simple Mode configuration Workflow Toolbar Scan Parameter List Window Scan 4 Channels Windows cae Scan Cobre Stage Citrate Toots brud e9uueiroa Reem ili scan Im iore gt Peak in Air Sean Stew 500 0m p Peakforce Aspect Patio x Offset 9 000 tes 0 000 rm Wu 0 877 He 92 Peak Force 0 1000 Y Engage Feedback Gain 5 000 Seanasyst Auto Control Cantilever Parameters 5 Scan 9 3000 N m 100 0m z Pei cece QNM Limits Raro DMTModulus Limit 1024 A
59. ters or FORCE nano Newtons 78 PeakForce QNM Rev F 5 6 Rev F Offline Analysis Image Math 5 5 3 Display Mode Change the Display Mode to PEAKF DEFLECTION VS SEP shown in Figure 5 5c to plot your data vs separation Line Plot Figure 5 5 Force vs separation nN Image Math You can use the IMAGE MATH functions in NanoScope Analysis software to re evaluate your results if you wish to change a parameter For instance you can re compute Young s modulus if you wish to compensate for a changed tip radius or a different spring constant Because you can scale Young s modulus by to arrive at corrected results Figure 5 6a shows an image of Young s modulus in a multilayer polymer optical film before correction Figure 5 6b shows an image of Young s modulus in a multilayer polymer optical film after multiplying it by 1 sqrt 2 to compensate for a tip radius that has increased by a factor of 2 e g from 10 nm to 20 nm PeakForce QNM 79 Offline Analysis Image Math Figure 5 6a Young s modulus in a multilayer polymer optical film before correction 2 00 Load Image 3m 5 sh 24nN Invert Image Figure 5 60 Young s modulus in a multilayer polymer optical film after Image Math correction Image Math e 00 3m 5 sh 24nN No Error
60. tivity Correction 1 08 Temperature Celsius 21 09 Spring Constant 0 06780 N m L Median Filter Width 5 B Markers Start Frequency 9792 Hz L End Frequency 35538 Hz HB Fit 1 03335 026 r vo 22421 342 Hz 0 0 000 7 25116e 018 391152 Hz 5 The microscope will acquire data for about 30 seconds 6 Zoom in on the region around the peak 60 PeakForce QNM Rev F Calibration Calibrate the Spring Constant Using Thermal Tuning 7 Click either the LORENTZIAN AIR or SIMPLE HARMONIC OSCILLATOR FLUID button to select a Lorentzian or a simple harmonic oscillator model respectively of the PSD to be least squares fit to the data Note The equations used to fit the filtered data are Lorentzian for use in air C Apt v vg Note where A v is the amplitude as a function of frequency v Apis the baseline amplitude Vo is the center frequency of the resonant peak C is a Lorentzian fit parameter is a Lorentzian fit parameter Simple Harmonic Oscillator for use in fluid Vo Ag Apc vov 2 2 vo v T where A v is the amplitude as a function of frequency v Apis the baseline amplitude Apc is the amplitude at DC zero frequency Vo is the center frequency of the resonant peak Q is the quality factor 8 Adjust the Median Filter Width shown in Fig
61. ultilayer polymer optical film before correctionz 2 case wie Mos olei La 80 Figure 5 6b Young s modulus in a multilayer polymer optical film after Image Math correction 80 Figure 5 6c The Image Math 81 Figure 5 64 The Image Math 81 Chapter 6 Index 24 56 DEPT 83 Rev F PeakForce QNM ix List of Figures x PeakForce QNM Rev F Chapter1 Introduction to PeakForce QNM Microscopy 1 1 Introduction PeakForce QNM Quantitative NanoMechanics an extension of Peak Force Tapping mode enables quantitative measurement of nano scale material properties such as modulus adhesion deformation and dissipation Because Peak Force Tapping Mode controls the force applied to the sample by the tip sample deformation depths are small and the effect of the substrate on the measured modulus is decreased PeakForce QNM can provide compositional mapping of a complex composite material while providing equal or higher resolution than a TappingMode image Snm Peak Force Tapping Mode has high spatial resolution relatively high speed and can detect a large range of elasticities PeakForce Tapping mode produces similar results to HarmoniX see the HarmoniX User Guide Bruker p n 004 1024 000 for details but is much easier to use and covers a wider modulus and adhesion range With a calibrated cantilever Peak
62. umber boxes display the Z piezo tap number You may move the force position by either dragging the dashed blue cursors in the image the dashed red cursors see Step 7 in the time display or entering the numbers in the Force Curve Selection panel You may select the channel of the captured image by right clicking in the image as shown in Figure 5 20 Figure 5 2c Vertical cursors display X position Image Line Selection Bl 1 EN Load Image Curve Selection _ Export Curves Pair Multiple 334 667 Restore Default E PeakForceQNM Input Parameters Force Curve Type Both Deformation Sens 168 nm V Deflection Sens 24 5 nm V Spring Constant 21 50 i li Hsdc Display Channel 1 Copy Clipboard L Retrace image from PS LDPE90 film 014 Channel 1 0 0 4 LogD Modulus 4 0 um 72 PeakForce QNM Rev F Offline Analysis Procedure The position of the force curves is also represented by the red dashed cursors in the Deflection Error vs Time display shown in Figure 5 2d To Zoom in on an area of interest in the graphs hold down the Control key and draw a box in the preferred area To Zoom back out double click the image or click the magnifying glass icon in the lower left corner of the plot Figure 5 2d The QNM Hsdc Force Curve Image window E PoakForcoQNnm Input Parameters Force Curve Both Defo
63. ure 4 4c to remove individual narrow spikes This replaces a data point with the median of the surrounding n n 3 5 7 data points Figure 4 4c Median Filter Width B Thermal Tune Thermal Tune Range 1 100 KHz PSD Bin Width 7 63 Deflection Sensitivity 60 00 nm V Deflection Sensitivity Corre 1 08 Temperature Celsius 21 09 Spring Constant 0 06780 L Median Filter Width 3 M B Markers i H Start Frequency L End Frequency 9 Adjust the PSD Bin Width to reduce the noise by averaging Rev F PeakForce QNM 61 Calibration Measure the Tip Radius 41 NanoScope Analysis 10 11 12 13 14 Drag markers in from the left and or right plot edges to bracket the bandwidth over which the fit is to be performed See Figure 4 4b Click FIT DATA The curve fit in red is displayed along with the acquired data If necessary adjust the marker positions and fit the data again to obtain the best fit at the thermal peak Enter the cantilever Temperature Click CALCULATE SPRING You will be asked whether you want to accept the calculated value of the spring constant k see Figure 4 4d Clicking OK copies the calculated spring constant to the Spring Constant window in the Cantilever Parameters window Figure 4 4d Spring Constant Calculation Result NanoScope Calculated Spring Constant is 0 0986 N m Do you want to use this value 4 5 Measure the Tip Radius
64. used eese dente dove tweens tite ie 52 Calibration cess ead aged ip A 53 4 1 Introduction to Calibrating PeakForce QNM 53 4 2 Absolute vs Relative Calibration Methods 53 42 1 The Relative Method iere roh er hh hr meh he n 55 4 2 2 The Absolute Method 2 ccc cece cece cee cee eere nnn 55 4 3 Calibrate the Deflection Sensitivity cece eee ee eee eee eee 56 4 4 Calibrate the Spring Constant Using Thermal Tuning 59 4 5 Measure the Tip Radius cece eee cee 62 4 6 Calibrate Peak Force 8 8 65 4 6 1 Cantilever Parameters cee cece ccc cee cee ree eee eee erences 66 4 6 2 Feedback Parameters cece cee cece cree cee eee eee eee nnn 66 Offline Analysis 69 5 IX Introd ctions cee eoe ee EL eI tee ete 4 69 5 2 Procedute REA erre eR AEGIS ERE RAN EE RE 69 5 3 Controls and Settings eect eee EA nn 74 5 3 1 Image Line Selection ein ern Enes cece cece reece enhn 74 5 32 Force Curve Selection ry 04 06 hes 75 5 3 3 Borce Curve RE ERU V ROCCO RE NS 76 5 3 4 Exporting Force Curves i ele 76 5 4 PeakForce QNM Input 76 5 5 Exported Force Curves c e
65. xpanded Mode Show All Other Dependencies Peak Force Yes Yes Yes Setpoint Feedback Gain Yes Yes Yes Low Pass Deflection No Yes xes Bandwidth ScanAsyst No No Yes Setup ScanAsyst Noise No ida Threshold 5 E ScanAsyst 5 Auto Config No No Yes E Frames ScanAsyst Yes Yes Yes Auto Control ScanAsyst Yes Yes Yes ScanAsyst Auto Control Auto Gain ScanAsyst Yes Yes Yes ScanAsyst Auto Control Auto Setpoint ScanAsyst Scan Auto Yes Yes Yes ScanAsyst Auto Control Scan Rate ScanAsyst Yes Yes Yes ScanAsyst Auto Control Auto Z Limit 34 PeakForce QNM Rev F PeakForce QNM Operation PeakForce QNM Parameters Panel Parameter Simple Mode Expanded Mode Show All Other Dependencies Peak Force No Yes Yes Amplitude Lift Height No Yes Yes lt Top Fit Region No No Yes 9 E Unload Fit No No Yes d Region Q P Deformation No No Yes Fit Region 2 Spring Yes Yes Yes Constant Tip Radius Yes Yes Yes 5 gt 2 Poisson s Ratio Yes Yes Yes Q Force Limit No Yes Yes 8 Dissipation No Yes Yes E Limit gt DMT Modulus Yes Yes Yes Limit o E LogDMT No No Yes Modulus Limit LogDMT Modulus No No Yes Offset Z Limit No No Yes 5 Y Y Y E Z Range es es es Deflection No Yes Yes Limit Rev F PeakForce QNM 35 PeakForce QNM Operation Capture Buttons 2 7 Capture Button

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