原子力显微镜AFM原理及操作手册

Page1©AsylumResearch2014AtomicForceMicroscopyPart2:StandardmodesandapplicationsAsylumResearchPage2©AsylumResearch2014•Commonmodesofoperation•Afewapplications•AfewNEWapplications!–andsomecoolimagesPrinciplesofAFMPage3©AsylumResearch2014•Forcemeasurements•Contactmode•AC(tapping)modeandsourcesoferrorinmeasurementsModesofOperationPage4©AsylumResearch2014SampleLightSourceFocusingOpticsCantileverPositionSensitiveDetectoryxzShakePiezoVarythetip-sampleseparation,usuallywithoutfeedback-50Deflection(nm)-1.6-1.2-0.8-0.4ZPosition(m)F=-kxModesofOperation–forcecurvesPage5©AsylumResearch2014DeflVolts[V]orDeflection[nm]orForce[N]Force=(DeflVolts)*(DeflInvOLS)*(k)[nN][V][nm/V][nN/nm]DeflectionTipsampledistance[nm]ModesofOperation–forcecurvesPage6©AsylumResearch2014k=21.4±0.4pN/nm15x10-12105PowerSpectrum(nm/ÃHz)14kHz121086420Frequency(kHz)12kA212kBTEquipartitiontheoremquantifiesthermal(Brownian)motion•Advantages-“standard”-non-destructive-easytouse•Disadvantages:-mustfirstcalibratesensitivity-valuesgoodtoonly±10%SpringconstantcalibrationModesofOperation–forcecurvesPage7©AsylumResearch2014ModesofOperation–forcecurvesPage8©AsylumResearch2014•ArraysofForcecurvescanbeusedtocalculatethelocalstiffnessofasampleModesofOperation–forcecurvesPage9©AsylumResearch20146420-2nm-4.8-4.6-4.4-4.2-4.0-3.8µmARTIFACTS–opticalinterferencePage10©AsylumResearch201420151050-5nm-50050nmARTIFACTS–tip/substrateinteractionPage11©AsylumResearch2014302520151050nm1.41.21.00.80.60.40.20.0µm0.5Hz5Hz10HzVelocity:Increasingvelocityaddshysteresisbetweenapproach&retractportionsofcurveARTIFACTS–hydrodynamiceffectsPage12©AsylumResearch2014BsurfacechargepullscantilevertosurfaceARTIFACTS–surfacechargingPage13©AsylumResearch2014LaserMirrorCantileverQuadPDSurfaceVtLaserMirrorCantileverQuadPDSurfaceVtLaserMirrorCantileverQuadPDSurfaceVtLaserMirrorCantileverSurfaceQuadPDtVSurfaceLaserMirrorCantileverQuadPDSurfaceLaserMirrorCantileverQuadPDSurfaceLaserMirrorCantileverQuadPDModesofOperation–contactmodePage14©AsylumResearch2014Tipsampledistance[nm]DeflVolts[V]PointoffirstcontactSetpointModesofOperation–contactmodeDeflectionfeedbackPage15©AsylumResearch2014ChangesinheightwhilescanningaredisplayedonthecomputerastopographyModesofOperation–contactmodePage16©AsylumResearch2014LaserMirrorCantileverQuadPDVSurfacetLaserMirrorQuadPDVCantileverSurfacetLaserMirrorCantileverQuadPDVSurfacetLaserMirrorQuadPDVCantileverSurfacetLaserMirrorCantileverQuadPDVSurfacetLaserMirrorCantileverQuadPDVSurfacetLaserMirrorCantileverQuadPDVSurfacetLaserMirrorCantileverQuadPDVSurfacetLaserMirrorCantileverQuadPDVSurfacetSurfaceLaserMirrorCantileverVtQuadPDSurfaceLaserMirrorCantileverQuadPDVtSurfaceLaserMirrorCantileverVQuadPDtSurfaceLaserMirrorCantileverQuadPDVtSurfaceLaserMirrorCantileverVtQuadPDModesofOperation–AC(tapping)modePage17©AsylumResearch2014Tip-sampledistanceAmplitudeSetpointFreeamplitudePointoffirstcontactModesofOperation–AC(tapping)modeAmplitudefeedbackPage18©AsylumResearch2014SampleLightSourceFocusingOpticsCantileverPositionSensitiveDetectoryxzShakePiezoZfeedback6050403020100µm6050403020100µmChangesinheightwhilescanningaredisplayedonthecomputerastopographyModesofOperation–AC(tapping)modePage19©AsylumResearch2014ARTIFACTS:TipSize&ShapeEffectsImageisnotequivalenttoaphotograph.Weseeaconvolutionofsamplesurfacewithshapeoftip.Tipmust‘fitin’betweensurfacefeatures.Aslongastipissmallerthanfeatures,accurateXYrepresentationofsurface.VeecoPage20©AsylumResearch2014ProbeSimulatorbyJosephGriffithSampleAFMTipMeasuredtopographyGoodTipBadTipReallyBadTipARTIFACTS:TipSize&ShapeEffectsPage21©AsylumResearch2014-1.0µm-0.50.00.51.0ZSensor121086420µm2umcubeparticles:ImagessideoftipSurfaceimagestipARTIFACTS:SurfaceimagesthetipPage22©AsylumResearch20142.01.51.00.50.0µm543210µm-40-2002040nm2.01.51.00.50.0µm543210µm-40-2002040nmARTIFACTS:FunkytipPage23©AsylumResearch201486%setpoint55%setpoint5umx5um10umpitchVLSIcalibrationgrid;ACmodeimageinair‘parachuting’goodtrackingARTIFACTS:ToomuchforceappliedPage24©AsylumResearch2014Integralgain=40Integralgain=2Integralgain=~95umx5umscan,10umpitchVLSIcalibrationgrid;ACmodeimageinairARTIFACTS:Feedbackloopeffects(highgain)Page25©AsylumResearch201448mV66mV500mV302520151050302520151050µm5umx5um100umpitchVLSIcalibrationgrid;ACmodeimageinairARTIFACTS:Feedbackloopeffects(driveamplitude)Page26©AsylumResearch2014302520151050µm302520151050µm-20-1001020nm-200nm-150-100-500Height2520151050µm302520151050µm302520151050µm-20-1001020nm-200nm-150-100-500Height302520151050µmARTIFACTS:ScanrateeffectsPage27©AsylumResearch2014ImagesApplicationsmeasurementsPage28©AsylumResearch2014250nmscanDNAinliquidImagesPage29©AsylumResearch2014ConsecutiveupanddownscansofasingleDNAmoleculeinbuffertakenwitha30µmleveratanamplitudeofabout8Å.Thenominalhelixpitchis3.4nm,withamajorgroovewidthof2.2nmandaminorgroovewidthof1.2nm.Youcansee6groovesalongthe10nmscalebar,soboththemajorandminorgrooveareclearlyresolved.DNAinliquidImagesPage30©AsylumResearch2014CourtesyofS.MacLarenandH.WangUniversityofIllinoisatUrbana-Champaign.E