Electron microscopes utilize a beam of energetic electrons to examine objects, overcoming the limitations of light microscopes. They are categorized into scanning electron microscopy (SEM), transmission electron microscopy (TEM), and others, allowing for high magnification and detailed analysis of surface features, morphology, composition, and crystallography. SEM is particularly versatile for studying non-metallic and biological materials without the need for coating, and it is widely used in forensic analysis.

1. Prepared by H
a
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2. lntroduction
• Electron microscopes are scientific instruments that the a
beamofenergetic electrons toexamine objects
• Electron microscopes weredeveloped dueto the limitations
ofLightMicroscopes.
• In 19JJ, there was a desire to see the fine detalls of the
interior structures of orgànic cells.
• This required 10,000d magnification which w
a
snot possible
lJSing 0ptiCül ItliCrOSCOpeS.
• T
y
p
e
sofElectronMicroscopy
1
. S
c
a
n
n
i
n
gElectronMicroscopy(
S
E
M
)
2. TransmissionElectronMicroscopy(TEM)
3. ScanningTransmission ElectronMicroscopy (
S
T
E
M
)
4. Analytical ElectronMicroscopy (AEM)

4. Detector
Anode
Electron Gun
Backscattered
Detector

5. F0RMAT|0NRETREVED
• TopoçrapL/—
T
hesurfacefeaturesonanobject.
• MorpLo!oçy —
Theshapeandsizeoftheparticles
• COM/40Sitior —
The elements and compounds that the
Object is composed of and the realative amounts of
them.
• CrystallographicInformation—How the atoms a
F
e
arrangedintheobject.

7. SeconØ Electroi
GeuÆion
-somp/eelexronsejectedbythe
primaç Ham(greenline]
-lowenergy
-suJacedeQil&toøgaphy

9. 1. SecondaryElectron
2. Back-scatteredElectrons
9
Ojtrsftllelttøríls fłlt ,

11. 1. SecondaryElectron
2. Back-scatteredElectrons
11

12. 1. SecondaryElectron
2. Back-scatteredElectrons
• In fEM, C
Ldetectors diS§lat anemission spectrum or an
image of the distribution of cathodoluminescence
emitted bythespecimenin real color.
• Verypowerful probe for studying naroscale features and

15. • Samples are observed in low pressure gaseous
environments andhighrelative humidit/ (upto100%).
• E
S
E
Misespecially useful for non- metallic andbiological
materials.
*Coatingorcarbonorgoldinunnecessary.
*Good for plastic ar elastoner$ a
n
d other unc0ate
b 0l0g Cül SülTl l6S
*ESEM makesit possible to performX-rayMicro analyses
onuncoated nonconductive SampleS.
*Preferred too!forForensicAnalysis.

16. APPÜC
AT|0
NS
S
E
Mis one of the most versatile technique and can b
e
usedfor:
Plmage morphology of samples
Plmage compositional andbondingdifferences
PExamine wet anddry samples while viewing them(only
inESEM)
(
E
D
1
)
üView or map grain orientation,crystallographic
oriertatior andstudyinformation likeLeteroçeneity.
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