Electron Microscopy (SEM & TEM)

Introduction to Electron Microscopy, Basic Introductory Idea, SEM & TEM, Basic Working Principles

1. KALYAN ACHARJYA
kalyan5.blogspot.in
Fundamental of Electronics (FOE)
UNIT-5
ELECTRON MICROSCOPY

2. UNIT 5
Electron Microscopy
Introduction to Nanotechnology

3. MICROSCOPE

4. How Compound Microscope Magnify:

5. Microscopy
Amicroscope-Greek:micron=
smallandscopos=aim
MICROSCOPE -Aninstrumentfor
viewingobjectsthataretoosmall
tobeseenbythenakedorunaided
eye.
MICROSCOPY -Thescienceof
investigatingsmallobjectsusing
suchaninstrumentiscalled
microscopy.

6. Historical Background
1590-HansJanssenandhissonZachariasJanssen,developed
firstmicroscope.
1609-GalileoGalilei-occhiolinoorcompoundmicroscope.
1620-ChristianHuygens,anotherDutchman,developeda
simple2-lensocularsystemthatwaschromaticallycorrected.

7. Microscopy History
AntonvanLeeuwenhoek(1961)-AntonvanLeeuwenhoekis
generallycreditedwithbringingthemicroscopetothe
attentionofbiologists.

8. Electrons Matter Interaction

9. References (Contents)
Dr SANTOSH KARADE Slides (SlideShare.net)
Wikipedia (For Images)
Researchgate.net (SEM & TEM Difference)
Disclosure
Only Use for Academic Purpose Only
Thank you for all Original owner of
Images and some contents

10. When we see the any objects?

11. Terms uses in Microscopy:
Magnification:Degreeofenlargement:Nooftimesthe
length,breadthordiameter,ofanobjectismultiplied.
RESOLUTION :Abilitytorevealcloselyadjacent
structuraldetailsasseparateanddistinct
LIMITOFRESOLUTION (LR):Themindistance
betweentwovisiblebodiesatwhichtheycanbeseenas
separateandnotincontactwitheachother
LR=(0.61xlamda)/NA
lamda= Wavelength, NA= Num aperture

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NUMERICAL APERTURE(NA)
•Ratio of diameter of lens to its focal length
•NA = n Sin θ/2
n = Refractive index,
θ= Angle of aperture (CAD)
θ/2
A
B
D
C
n of air = 1 n of oil = 1.5

13. Types of Microscope
Simple microscope
Compound microscope
Phase Contrast Microscope
Dark Ground Microscope
Fluorescent Microscope
Electron Microscope..etc

14. General Comparison
Types of MicroscopeResolution Power
Compound Microscope 200 nanometers
Scanning Electron
Microscope
10 nanometers
Transmission Electron
Microscope
0.2 nanometers

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ELECTRON MICROSCOPE
ElectronMicroscopesusesabeamofhighlyenergetic
electronstoexamineobjectsonaveryfinescale.This
examinationbringsthedetailsabouttheobservant.
Topography
Morphology
Composition
CrystallographicStructure

16. 16
TYPES OF ELECTRON MICROSCOPE
Scanning Electron Microscope (SEM)
Transmission Electron Microscope (TEM)

17. 17
SEMfocusesonthesample’ssurfaceanditscomposition
Scanagold-platedspecimentogivea3-Dviewofthe
surfaceofanobjectwhichisblackandwhite.
Usedtostudysurfacefeaturesofmaterials,cellsand
viruses.
ScanningElectronmicroscopehasresolution1000times
betterthanLightmicroscope.
SCANNING ELECTRO MICROSCOPE

18. SEM Microscope Image: University of Alberta

19. SEM Structure (Two Examples)

20. SEM Images (Micron Range)
Vibriocholeraewith polar Flagella

21. SEM Images (House Fly)
Image Courtesy: www.groundzeroweb.com

22. SEM Images Bacteria on the surface of a human tongue
Image
Courtesy:http
://
izismile.com

23. SEM Images
This is a platinum wire that has been milled to 50nmin
diameter. It is to be used a gas sensor.
Image Courtesy: http://www.onelargeprawn.co.za

24. SEM Images Human Eye

25. SEM Images Ant Holding a Microchip
Image
Courtesy:http
://
izismile.com

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TRANSMISSION ELECTRON MICROSCOPE
(TEM)-STEM-Scanning TEM
Streamofelectronsisformed.
Acceleratedusingapositiveelectricalpotential
FocusedbymetallicapertureandElectromagnets
Interactionsoccurinsidetheirradiatedsamplewhichare
detectedandtransformedintoanimage.
Scanningelectronmicroscopyallowsforhighermagnificationand
betterresolutionthanstandardlightmicroscopy.
Sincethesampleisbombardedwithelectronsratherthanlight,
thelevelofdetailinasmallerareaismuchgreaterthanalight
microscope

27. TEM Microscope

28. Diffraction:
Image Courtesy: Wiki

29. TEM-Transmission Electron Microscope
Image Source: Encyclopedia Britannica

30. TEM Images

31. TEM Images
A transmission electron microscope image of
Apple A7 28nm NMOS transistors.
Image Courtesy: E Times of India

32. SEM vs. TEM
SEMisbasedonscatteredelectronswhileTEMisbasedon
transmittedelectrons.
SEMfocusesonthesample’ssurfaceanditscompositionwhereas
TEMprovidesthedetailsaboutinternalcomposition.Therefore
TEMcanshowmanycharacteristicsofthesample,suchas
morphology,crystallization,stressorevenmagneticdomains.On
theotherhand,SEMshowsonlythemorphologyofsamples.
ThesampleinTEMhastobecutthinnerwhereasthereisno
suchneedwithSEMsample.
TEMhasmuchhigherresolutionthanSEM.
SEMallowsforlargeamountofsampletobeanalyzedatatime
whereaswithTEMonlysmallamountofsamplecanbeanalyzed
atatime.

33. SEM vs. TEM
SEMisusedforsurfaces,powders,polished&etched
microstructures,ICchips,chemicalsegregationwhereas
TEMisusedforimagingofdislocations,tinyprecipitates,
grainboundariesandotherdefectstructuresinsolids
InTEM,picturesareshownonfluorescentscreenswhereas
inSEM,pictureisshownonmonitor.
SEMalsoprovidesa3-dimensionalimagewhileTEM
providesa2-dimensionalpicture.
TEMrequiresextensivesamplepreparation.Thethickness
ofthespecimenstobeexaminedunderTEMshouldbeless
that100nm.

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Advanced MICROSCOPES
SCANNING PROBEMICROSCOPE -Classof
Microscopethatmeasuressurfacefeaturesby
movingasharpprobeoverobjectsurface.
Usedtovisualizeatomsandmoleculesin
moredistinctly.
Scanning Tunneling Microscope (STM)
Atomic Force Microscope (AFM)

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