KhaledKAJA®–AFM2019

AtomicForceMicroscopyIntroduction,Foundations,

InstrumentationandMulti-disciplinaryApplications

Aseriesoflecturesby

Dr.KhaledKaja

DNAdoublehelixstructureresolved

AlkanechainsC36H74StudyofGraphene’sstructural,electricalandchemicalproperties

KhaledKAJA®–AFM2019

AbstractAtomicForceMicroscopy(AFM)hasrapidlygrownsinceitsinventionin1986tobecomeanessentialtechniqueforsurfacecharacterizationinlargevarietyofresearchfieldsinnano-electronics,materialssciences,polymers,softmatter,chemistryandbio-technologicalapplications.AFMenablestheinvestigationofsurfaceandsub-surfacepropertiesofsamplesatanunprecedentedscaleoffewnano-metersandultimatelyattheatomiclevel.

Theimportanceofthistechniqueinvirtuallyallfieldsofresearchraisestheneedofaclearunderstandingofitsfundamentalfoundationsandprinciples.Thedevelopmentofnumerousmodestailoredtovariousapplicationsmakesitessentialtounderstandthedifferentoperationprinciplestoprovidegraduatestudentswithsufficienttheoreticalandexperimentalbackgroundtopropeltheirresearchforwardandexplorenovelapplicationsandpublishableresults.

TowhomtheselecturesareaddressedTheselecturesareintendedforundergraduateandgraduatestudentswhoarelookingtotaketheendeavorinthefieldofnano-sciences.ThiswillcoverstudentsworkinginthefieldofPhysics,Electronics,ElectricalEngineering,Polymers,Organicchemistry,SoftmatterandBiology.

ThetopicsaddressedintheselecturesaretailoredtointroducethestudentstothefieldofScanningProbeMicroscopy(SPM)fortheiruseandapplicationinavarietyofsystems’characterizationandstudies.Mainbeneficialofthisare:

• Masterstudentspreparingtoenrollinfutureresearchstudiesinvolvingcharacterizationandinvestigationatthenano-scale.

• PhDstudentsinthecourseoftheirresearchstudies.• Scientistsandresearcherslookingtoexpandtheirfieldandseekingadeep

understandingoffundamentalaspectsofAFMaswellasinstrumentationaspectsanddevelopment.

KhaledKAJA®–AFM2019

Outline

Thisseriesoflecturesaredistributedtotwomainmodules:

AFMI:Introduction&Foundations–AtheoreticalbackgroundinAtomicForceMicroscopy.

AFMII:Multi-modal&Multi-disciplinaryApplications–Anin-depthstudyofAFMbeyondtopographyanditsapplicationsinnano-electronics,nano-magnetism,chemistryandbio-technology.

KhaledKAJA®–AFM2019

CoursesContent

AFMI

Introduction&FoundationsAtheoreticalbackgroundinAtomicForceMicroscopy

1. IntroductiontoScanningProbeMicroscopy:

1.1. HistoricalBackground1.2. TheInventionoftheScanningTunnelingMicroscope:principle1.3. TheNeedforaForceMicroscopy:inventionoftheAFM1.4. WhatisanAFMandwhatdoesitmeasure?Overviewdescription1.5. AFMandNanosciences:applicationsoverviewandinterests1.6. OverviewofAFMmodesandexperimentaladaptations

2. ForcesinAtomicForceMicroscopy:2.1. OverviewofForcesfeltbyanAFMprobe2.2. ElectrostaticForces:

2.2.1. Coulomb’slawforpointcharges2.2.2. Electrostaticpotentialenergy

2.3. Moleculardipolemoments2.4. Dipolemomentsinexternalelectricfields2.5. SimplemodelsforMolecule-Moleculeinteractions:

2.5.1. InteractionofanIonwithamolecule2.5.1.1. Ioninteractingwithafixedpolarmolecule2.5.1.2. Ioninteractionwithapolarmoleculefreetorotate2.5.1.3. Induction:thepolarizationofanon-polarmolecule2.5.1.4. Interactionofapointchargewithanon-polarmolecule

2.5.2. Molecule-Moleculeinteractions2.5.2.1. Interactionoftwopolarmolecules2.5.2.2. Angle-averagedinteractionbetweentwopolarmolecules2.5.2.3. Interactionbetweenadi-polarmoleculeandanon-polarmolecule2.5.2.4. Interactionbetweentwonon-polarmolecules

2.6. VanderWaalsforcesbetweenmacroscopicobjects2.7. SurfaceEnergy,AdhesionandHamakerconstant2.8. TheDerjaguinApproximation2.9. Capillaryforces

KhaledKAJA®–AFM2019

2.10. Frequencydependentdielectricfunction3. ContactMechanics

3.1. Elasticityofmaterials:3.1.1. Young’smodulus3.1.2. Poisson’sratio

3.2. Repulsiveinteractions:3.2.1. Hertzcontactmechanics3.2.2. DMTcontactmechanics3.2.3. JKRcontactmechanics3.2.4. Maugis–Dugdalemodel

3.3. Tip-surfacecontactinteractioninAFM:introducingforcespectroscopy3.3.1. Forcecurves3.3.2. Derivingsurfacepropertiesfromforcecurvesmeasurements

4. TheAFMinstrument4.1. GenericdescriptionofanAtomicForceMicroscopycomponents4.2. TheAFMprobe:

4.2.1. Deflectionofrectangularbeams4.2.2. Springconstant4.2.3. TheAFMcantileverasavibrationalbeam:eigenmodes4.2.4. Thermalvibrationsofthecantilever4.2.5. Spectralpowerdensity4.2.6. DesignandfabricationofAFMprobes:recenttrendsandneeds

4.3. TheAFMscanner:4.3.1. Measurementofdisplacements4.3.2. Steppermotors4.3.3. Theprocessofthetipapproach4.3.4. X-Yscanners:piezocreep

4.4. Thetransductionofthetip-sampleforces:4.4.1. Theopticalleverbeam4.4.2. Thephotodiodedetector4.4.3. Othermodesofmeasuringthedeflectionofthecantilever

4.5. Thefeedbackloop4.6. Thescanningofthesurface:methods4.7. TheformationofanAFMimage4.8. Imageprocessingtools4.9. Minimizingthethermaldrift4.10. Reducingfloorvibrations

5. Forcespectroscopy:Forcecurvesmeasurementsandcalibrations

KhaledKAJA®–AFM2019

5.1. MeasuringforceversusZ-displacement5.1.1. Z-scannermovement:ramping

5.2. DerivingForce-distancecurves:sampledeformation5.3. Calibrationoftheforce:

5.3.1. Calibratingthespringconstantofthecantilever:methods5.3.2. Calibratingthedeflectionsensitivity5.3.3. Sourceoferrorsanduncertaintiesinthecalibrationprocess

5.4. Forcecurvesinair:5.4.1. Thejumpintocontact5.4.2. Thequestionofzeroforceposition

5.5. Forcecurvesinliquids5.6. Importanceofforcecurvesmeasurements:

5.6.1. Young’smodulusandadhesion5.6.2. Functionalizationoftheprobe5.6.3. Bindingandunfolding5.6.4. Longrangeinteractionsinvolved

5.7. Commondifficultiesinforcecurvesmeasurements5.8. Processingofforcecurvesdata

6. AFMincontactmode6.1. Imagingprocess:

6.1.1. Constantdeflection6.1.2. Feedbackgains6.1.3. Lateralforces–lateralforceimaging6.1.4. AdvantagesanddrawbacksofAFMincontactmodes6.1.5. Spatialresolutionincontactmode6.1.6. Nano-lithographyandlocalanodicoxidation

7. NoiseinAFM7.1. Externalsources7.2. Groundloopproblems7.3. Thermalfluctuations7.4. Measuringthesignaltonoiseratio7.5. Electronicnoises

KhaledKAJA®–AFM2019

CoursesContent

AFMII

Multi-modal&Multi-disciplinaryApplicationsIn-depthstudyofAFMbeyondtopography

Applicationsinelectronics,magnetism,chemistryandbio-technology1. DynamicAFMmodes

1.1. VibrationsoftheCantilever1.1.1. Excitationmodes1.1.2. Probeholdersandinstrumentalconsiderations1.1.3. Eigenmodesandharmonics1.1.4. Energyofthecantilever’svibrationmodes1.1.5. Perspectives

1.2. Detectionofthecantilever’soscillations1.2.1. Drivingsignal,oscillationsandtheconceptofphase1.2.2. Lock-inamplifiers:reference,amplitudeandphaseoutputs

1.3. Oscillationsofanexcitedcantilever–vibrations1.3.1. Theconceptofresonance1.3.2. Theresponsecharacteristicsofanoscillatingcantilever

1.4. ThePhysicsoftheoscillatingcantilever1.4.1. Thespring-massmodel1.4.2. Thesimpleharmonicoscillator1.4.3. Dampedandforcedoscillatingcantilever1.4.4. Presenceofsurfaceinteractions:forcegradient1.4.5. Solutionoftheequationofmotion:amplitudeandphaseresponses1.4.6. Approximationofsmallamplitudes:linearapproximation

1.5. Tappingmode–Amplitudemodulation1.5.1. Principleofoperation1.5.2. Analysisoftheamplitude–Qfactor1.5.3. Sensitivity1.5.4. Analysisofthephase1.5.5. Calibration:amplitudevsdistanceandphasevsdistancecurves1.5.6. Attractiveandrepulsiveregimes:

1.5.6.1. TheLennardJonespotential

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1.5.6.2. Intermittentcontactregion1.5.6.3. Amplitudeandphasecurves1.5.6.4. Operationregimesandbi-stability

1.5.7. Spatialresolutionintappingmode:considerationsandregimes1.5.8. ImagingchannelsinTappingmode1.5.9. Phaseimagingandoriginofcontrast–compositionalmapping1.5.10. Non-linearityintheintermittentcontactmode

1.5.10.1. Viriel1.5.10.2. Harmonicmethod1.5.10.3. TheDuffingoscillator

1.5.11. Dampinginamplitudemodulation1.5.11.1. Timeconstant,Qfactorandequilibriumstates

1.5.12. Tappingmodeinliquid1.6. TheNon-contactmode–Frequencymodulation

1.6.1. Regionofoperation1.6.2. Frequencyshiftandnatureofforces1.6.3. PhaseLockLoop(PLL)–bandwidth1.6.4. Principleofoperation1.6.5. Damping,dissipationandfrequencyshifts1.6.6. Q-factorandProbes:Q-plus,Kolibriandlengthextensionresonators1.6.7. Operationinvacuum:advantages1.6.8. SpatialresolutioninNCAFM1.6.9. Derivingtheforcesfromthefrequencyshiftcurves

1.7. PeakForceTapping1.7.1. Semi-static,semi-dynamicmode:principleofoperation1.7.2. TheneedtointroduceanewwayofAFMoperation1.7.3. SinusoidalmodulationinZversusRampingmotion1.7.4. Forcecontrol1.7.5. Cantileverresponseandcalibrations1.7.6. Equationofmotion?

2. MechanicalProperties:modesandapplications2.1. Forcespectroscopy

2.1.1. MeasuringlocalElasticpropertiesandAdhesion2.1.2. Measuringthebendingmodulusofsuspendedstructures2.1.3. Examples

2.2. ForceVolumemode2.2.1. Principleofoperation2.2.2. Calibrations

KhaledKAJA®–AFM2019

2.2.3. Imagingchannels:modulus,stiffness,adhesion2.2.4. Imageprocessing2.2.5. Challenges,limitationsanddifficulties2.2.6. Examples

2.3. Contactresonancemode2.3.1. Storageandlossmoduli2.3.2. Principleofoperation2.3.3. Modelsanddataanalysis2.3.4. Frequencyshiftsandtracking2.3.5. Examples

2.4. PeakForceQuantitativeNano-mechanicalMapping2.4.1. Principleofoperation2.4.2. Forceversusseparationcurves2.4.3. Calibrationoftheforceanddeflection2.4.4. Extractionandmappingofmechanicalproperties2.4.5. TheDMTmodelandcalibrations2.4.6. Challengesandperspectiveimprovements2.4.7. Examples

2.5. ApplicationsofmechanicalmeasurementsinAFM2.5.1. Materialssciences:polymers,novel2Dmaterials,nano-wiresandnano-tubes2.5.2. Biologyandbio-technology:cells,cancer,diseases,collagenandfibrils

3. Electricalandelectronicproperties:modesandapplications3.1. IntroducingtheLiftmodeoperation

3.1.1. Doublescanmode3.1.2. Linearscanmode

3.2. ElectricForceMicroscopy3.2.1. Capacitiveforceandmodulation3.2.2. Measuringindividualcharges3.2.3. Artifacts

3.3. Kelvin(Probe)ForceMicroscopy3.3.1. Theoryoftheworkfunction3.3.2. Importanceoftheworkfunctioninvariousapplications3.3.3. Generalprincipleofoperation:amplitudemodulationKPFM3.3.4. Resolutionandcontrast3.3.5. FrequencymodulationKPFM3.3.6. Probes3.3.7. Examples

3.4. PiezoresponseForceMicroscopy

KhaledKAJA®–AFM2019

3.4.1. Principleofoperation3.4.2. Resonanceofdoublefixedrectangularlever3.4.3. Examples

3.5. ConductiveAFM(TUNA,PFTUNA)3.5.1. Modelsofcurrentflow3.5.2. MeasuringcurrentwithanAFMprobe:rangeofcurrents3.5.3. ContactmodesandPeakForcecurrentmeasurements3.5.4. Examples

3.6. ScanningCapacitanceMicroscopy3.6.1. Dopantprofiling3.6.2. Principleofoperation3.6.3. Calibrationandquantification3.6.4. Examples

3.7. ScanningSpreadingResistanceMicroscopy3.7.1. Principleofoperation3.7.2. Modelofthespreadingresistance3.7.3. Amplificationandelectronics3.7.4. Examples

3.8. ScanningMicrowaveImpedanceMicroscopy3.8.1. TheoryofMicrowaveandimpedance3.8.2. Principleofoperation3.8.3. Instrumentalimplementation3.8.4. Examples

3.9. ApplicationsofelectricalpropertiesmeasurementsinAFM4. Magneticproperties

4.1. MagneticForceMicroscopy4.2. Applicationsindatastorageandmemorytechnologies

5. Chemicalproperties5.1. FourierTransformInfra-Red(FTIR)5.2. NovelcombinationofAFMandFTIR

6. Multi-modalCombinations:measuringdifferentpropertiessimultaneously7. FastScanningAFM

7.1. Applicationsneeds7.2. Challengesandtechnologicaldifficulties7.3. PhysicsoffastscanninginAFM7.4. Technologicalsolutions:

7.4.1. Probe7.4.2. Scanner

KhaledKAJA®–AFM2019

7.4.3. Modeofoperation7.5. Examples

8. Biologicalpropertiesandapplications8.1. Dynamicsofbiologicalphenomena8.2. Forcecontrol:imagingDNA8.3. Unfoldingofproteins–tipfunctionalization8.4. Elasticityofcellsandapplicationstocancerstudies8.5. Collagenandcollagenfibrils8.6. Electricalpropertiesofbiologicalsystems

9. Atomicandsub-atomicresolutioninAFM9.1. Physicalconsiderations9.2. Technicalconsiderations9.3. Samplepreparation9.4. Operatingmodesandenvironment9.5. Imagingmoleculesandelectronclouds9.6. Challengesanddifficulties

10. PracticalaspectsinAFM:tipsandtricks10.1. Probechoiceandcharacteristics10.2. Samplepreparationandapplications10.3. Complexsetupsanddevelopment10.4. Imageanalysis

10.4.1. Artifacts10.4.2. Dataprocessingandfiltering

10.5. HowtorecognizeagoodAFMandacorrectAFMimage

KhaledKAJA®–AFM2019

Supportingreferencesandtextbooks

• “IntermolecularandSurfaceForces”,JacobN.Israeilachvili,ElsevierInc.• “FundamentalsofAtomicForceMicroscopy,Part1:Foundations”,Ronald

Reinferberger,WorldScientific.• “SurfacesandInterfacesofSolidMaterials”,HansLuth,SpringerStudyEdition.• “SolidStatePhysics”,N.Aschcroft,N.D.Mermin,CengageLearning.• “CoursdeMicroscopieaForceAtomique”,FrancoisBertin,CEA-Leti.• “TheFeynmanlecturesonPhysicsVol.II:Electromagnetism“

KhaledKAJA®–AFM2019

TheLecturerDr.KhaledKajahasaPhDinNanophysicsfromthe French Authority of Atomic Energy (CEA)and the University of Grenoble I (JosephFourier) in France. He has been a researchassociate at the Swiss Federal Institute ofTechnology (ETH) in Zürich at the Chair ofNanotechnology.Heworkedasanapplicationsscientist at Bruker Nano-Surfaces (LeadingmanufacturerofAtomicForceMicroscopesandsurface characterisation techniques) based intheUK.Hewasresponsibleforallresearchandindustrial applications in the United Kingdom,Ireland, northern Europe region and themiddle-east. In the course of his research and

applications work, Dr. Kaja developed new operation AFM modes and demonstrated latestadvances and technologies in the field. He presented technical lectures in prestigiousuniversities in the UK such as Cambridge, Manchester, Leeds, Imperial College London andothers. He also organised numerous workshops and lectures in northern Europe andScandinavian regions such as Twente University in the Netherlands, University of Lunds inSwedenandHelsinkiinFinland.Dr.Kajahasover9yearsofexperienceinAtomicForceMicroscopytechniques.Hismainfieldsof interest are in Nanoelectrical and Nanomechnical techniques for surface characterisationwithafocusontwo-andlow-dimensionalmaterials.