SEM Midterm Exam Questions with Correct Answers Already Passed
2 different types of pollen - Answers polar and apolar
Apertures of pollen - Answers colpus (furrow), pore (circular opening), and colporate (furrow shaped
groove with central pore)
Different views of pollen - Answers polar, equatorial, and closeup
polar pollen has apertures arranged where - Answers at the equator
Apolar pollen has apertures arranged where - Answers scattered apertures, no equator
pollen sculpturing - Answers the outer surface relief or topography of a pollen grain or spore
Explain pollen preparation - Answers 41.) acetolysis gets rid of the cytoplasm inside the grain and the
waxes on the outside of the grain - prevents charging by these factors
2.) deflocculation: boiling in water bath, KOH (5%) mix, boiling again and strain through mesh,
centrifuging, wash with DIH2O, glacial acetic acid to dehydrate, mix and centrifuge, and then acetolysis
mixture (mix of acetic anhydride and sulfuric acid)
3.)Acetolysis: boil mix, centrifuge, dump and wash with glacial acetic acid, centrifuge and dump, wash
with DIH2O, centrifuge and dump until acid smell is gone - complete by placing a droplet on a stub with
carbon tape and dry in vacuum container
4.) sputter coat
Anton Van Leeuwenhoek - Answers developed simple lense
Ernst Abbe - Answers theory of image formation
Hans Busch - Answers produced first magnetic lens
Hugo Stintzing - Answers first theoretical description of SEM
Helmut Ruska and Max Knoll - Answers built first TEM and had first EM images
Max Knoll - Answers Built earliest SEM
Manfred von Ardeene - Answers 1st SEM that could handle bulk
Zworkin, Hillier, and Snyder - Answers Built first modern SEM
McMullan and Oatly - Answers built the Cambridge scope
Everhart and Thornley - Answers improved SE detector (improved signal to noise ratio)
Crewe and Wells - Answers produced 1st true STEM (combination of TEM and SEM)
,Rohrer and Binning - Answers developed scanning tunneling EM
How do forensics use SEM - Answers Test gun shot residue
Analyzing trace materials
How do metallurgy use SEM - Answers Analysis of cracks and defects in metal parts
Quantitive analysis of elemental components
How do you use SEM for paints - Answers Analysis of paints - components, layers, authenticity
How do big pharma use SEM - Answers Elemental analysis of capsules, tablets, other meds
Hydration and dehydration studies
How do big electronics and use - Answers Check circuitry and components
Verify small measurements
How do you use SEM for scientific research - Answers Nanoparticles and nanofibers
Films
Microstructures of plants, sands, and crystal structures
Depth of focus - Answers how much of sample is in focus at one time - SEM image gives 3-D appearance
due to large dof
Working distance, focal length, or Z - Answers distance between final lens and specimen (controlled with
joystick)
Magnification - Answers changes the length of sample scanned (higher mag, smaller scan size)
As dof decreases, what happens to WD, mag, and res? - Answers WD decreases, mag increases, res
increases
As dof increases, what happens to WD, mag, and res? - Answers WD increases, mag decreases, res
decreases
What are the two types of detectors - Answers E-T (Everhart-Thornley) or SE detector and BSD
(Backscattered Electron Detector)
E-T (Everhart-Thornley) or SE detector - Answers Detects mostly secondary electrons and some
backscattered electrons
Picks up and collects SE and some BSE electrons due to a positive voltage applied to the "cage"
BSD (Backscattered Electron Detector) - Answers 4 quadrant detector located under the final lens
, Negative voltage on the detector collection quadrant will repel lower energy secondary electrons and
collect the higher energy back scattered electrons
4 parameters that determine sharpness of the features in your image - Answers 1.) Electron probe size
or spot size (dp)
2.) Electron probe current - AKA i probe (ip)
3.) Electron probe convergence angle (alpha p)
4.) Electron beam accelerating voltage (V0), kV (EHT - extra high tension)
Electron probe size (dp) - Answers Diameter of the final beam at the surface of the specimen
Electron probe current - AKA i probe (ip) - Answers Current that hits the specimen and generates various
imaging signals (SE, BSE, x-rays, etc.)
Electron probe convergence angle (alpha p) - Answers The ½ angle of the cone of electrons converging
on the specimen
Electron beam accelerating voltage (V0), kV (EHT - extra high tension) - Answers As the voltage is
increased, the electrons travel with higher velocity and become more energetic
4 major imaging modes - Answers 1.)Resolution mode
2.)High-current mode
3.)Depth-of-focus mode
4.)Low-voltage mode
Resolution mode - Answers In this mode: dp must be as small as possible while maintaining a sufficient
ip
Produces a clear image of the sample's surface details
Used in high image magnification (>10,000X)
High-current mode - Answers Large ip is required
Details of specimen's low contrast features will improve
Depth-of-focus mode - Answers Must have alpha p as small as possible
Will increase the depth of field
Low-voltage mode - Answers Have voltage under 5kV, beam interacts with surface to provide rich
surface details (might lower image resolution however!)
2 different types of pollen - Answers polar and apolar
Apertures of pollen - Answers colpus (furrow), pore (circular opening), and colporate (furrow shaped
groove with central pore)
Different views of pollen - Answers polar, equatorial, and closeup
polar pollen has apertures arranged where - Answers at the equator
Apolar pollen has apertures arranged where - Answers scattered apertures, no equator
pollen sculpturing - Answers the outer surface relief or topography of a pollen grain or spore
Explain pollen preparation - Answers 41.) acetolysis gets rid of the cytoplasm inside the grain and the
waxes on the outside of the grain - prevents charging by these factors
2.) deflocculation: boiling in water bath, KOH (5%) mix, boiling again and strain through mesh,
centrifuging, wash with DIH2O, glacial acetic acid to dehydrate, mix and centrifuge, and then acetolysis
mixture (mix of acetic anhydride and sulfuric acid)
3.)Acetolysis: boil mix, centrifuge, dump and wash with glacial acetic acid, centrifuge and dump, wash
with DIH2O, centrifuge and dump until acid smell is gone - complete by placing a droplet on a stub with
carbon tape and dry in vacuum container
4.) sputter coat
Anton Van Leeuwenhoek - Answers developed simple lense
Ernst Abbe - Answers theory of image formation
Hans Busch - Answers produced first magnetic lens
Hugo Stintzing - Answers first theoretical description of SEM
Helmut Ruska and Max Knoll - Answers built first TEM and had first EM images
Max Knoll - Answers Built earliest SEM
Manfred von Ardeene - Answers 1st SEM that could handle bulk
Zworkin, Hillier, and Snyder - Answers Built first modern SEM
McMullan and Oatly - Answers built the Cambridge scope
Everhart and Thornley - Answers improved SE detector (improved signal to noise ratio)
Crewe and Wells - Answers produced 1st true STEM (combination of TEM and SEM)
,Rohrer and Binning - Answers developed scanning tunneling EM
How do forensics use SEM - Answers Test gun shot residue
Analyzing trace materials
How do metallurgy use SEM - Answers Analysis of cracks and defects in metal parts
Quantitive analysis of elemental components
How do you use SEM for paints - Answers Analysis of paints - components, layers, authenticity
How do big pharma use SEM - Answers Elemental analysis of capsules, tablets, other meds
Hydration and dehydration studies
How do big electronics and use - Answers Check circuitry and components
Verify small measurements
How do you use SEM for scientific research - Answers Nanoparticles and nanofibers
Films
Microstructures of plants, sands, and crystal structures
Depth of focus - Answers how much of sample is in focus at one time - SEM image gives 3-D appearance
due to large dof
Working distance, focal length, or Z - Answers distance between final lens and specimen (controlled with
joystick)
Magnification - Answers changes the length of sample scanned (higher mag, smaller scan size)
As dof decreases, what happens to WD, mag, and res? - Answers WD decreases, mag increases, res
increases
As dof increases, what happens to WD, mag, and res? - Answers WD increases, mag decreases, res
decreases
What are the two types of detectors - Answers E-T (Everhart-Thornley) or SE detector and BSD
(Backscattered Electron Detector)
E-T (Everhart-Thornley) or SE detector - Answers Detects mostly secondary electrons and some
backscattered electrons
Picks up and collects SE and some BSE electrons due to a positive voltage applied to the "cage"
BSD (Backscattered Electron Detector) - Answers 4 quadrant detector located under the final lens
, Negative voltage on the detector collection quadrant will repel lower energy secondary electrons and
collect the higher energy back scattered electrons
4 parameters that determine sharpness of the features in your image - Answers 1.) Electron probe size
or spot size (dp)
2.) Electron probe current - AKA i probe (ip)
3.) Electron probe convergence angle (alpha p)
4.) Electron beam accelerating voltage (V0), kV (EHT - extra high tension)
Electron probe size (dp) - Answers Diameter of the final beam at the surface of the specimen
Electron probe current - AKA i probe (ip) - Answers Current that hits the specimen and generates various
imaging signals (SE, BSE, x-rays, etc.)
Electron probe convergence angle (alpha p) - Answers The ½ angle of the cone of electrons converging
on the specimen
Electron beam accelerating voltage (V0), kV (EHT - extra high tension) - Answers As the voltage is
increased, the electrons travel with higher velocity and become more energetic
4 major imaging modes - Answers 1.)Resolution mode
2.)High-current mode
3.)Depth-of-focus mode
4.)Low-voltage mode
Resolution mode - Answers In this mode: dp must be as small as possible while maintaining a sufficient
ip
Produces a clear image of the sample's surface details
Used in high image magnification (>10,000X)
High-current mode - Answers Large ip is required
Details of specimen's low contrast features will improve
Depth-of-focus mode - Answers Must have alpha p as small as possible
Will increase the depth of field
Low-voltage mode - Answers Have voltage under 5kV, beam interacts with surface to provide rich
surface details (might lower image resolution however!)
