SEM Test1

SEM Test1
Q 1: 1.In most cases when X-rays pass through matter their intensity will
be _________________.
unchanged
enhanced
reduced
corrected
Q 2: In this schematic drawing of a scanning electron microscope, which labeling scheme is correct? (1) – electron gun (2) – backscattered electron detector (3) – secondary electron detector
A = 1,
B = 2,
C = 3
A = 1,
B = 3,
C = 2
A = 2,
B = 3,
C = 1
A = 3,
B = 2,
C = 1
Q 3: Where inside an SEM is the Backscattered Electron Detector located?
Below the sample
All around the sample
Immediately below the objective lens
Can be inserted within the SEM column in any position
Q 4: The picture above shows a mixed mineral sand from Dunwich that have been dusted onto an adhesive carbon tab, coated with carbon and imaged on the JSM 6460LA using one of the backscatter detector modes. Based on this data and your knowledge of compositional back scattered electron images, which is the most likely correct order for the 3 labelled
particles if they are ranked from highest average atomic number to lowest atomic number.
1; 2; 3
3; 2; 1
2 ; 3, 1
1; 3; 2
3; 1; 2
Q 5: What is the most commonly used name for the inelastic scattering process whereby primary beam electrons knock out other electrons from their shells?
Inner-shell ionization
X-ray ionization
Inner electron emission
Inner-shell X-ray emission
Q 6: When a high voltage electron beam strikes a specimen, how is most of the energy dispersed?
X-rays
Heat
Secondary electrons
Backscattered electrons
Q 7: The electron beam creates an interaction volume in a sample. Where are the X-rays generated from within this volume?
at the surface only
in the thin top layer (black layer) only
in the middle (grey) layer only
throughout the entire interaction volume
in the lower region (white area) only
Q 8: What labeling scheme of the SEM shown in this photograph is correct? 1. Secondary electron detector 2. X-ray detector 3. Specimen chamber 4. OL aperture
A = 1,
B = 2,
C = 3,
D = 4
A = 1,
B = 2,
C = 4,
D = 3
A = 2,
B = 3,
C = 4,
D = 1
A = 2,
B = 4,
C = 3,
D = 1
Q 9: What is the reason for using slow scan rates to accumulate micrographs?
The electron beam is more stable
The signal-to-noise ratio is improved
The resolution is enhanced
There is time to get a drink of water
Q 1
The best way to conduct experiments and get results using a SEM is?
0:
To know about the technique, the theory, the procedures, how to prepare the samples and ask the technician to do the experiments because a scientist just need to interpret results and doesn’t need to directly conduct experiments
To know about the technique, the theory, the procedures, and ask the technician to prepare the samples because a scientist just need to interpret results and directly conduct experiments but has no time to spend preparing routine samples
Have a meeting with the technician and carefully explain him/her all the particulars of the experiment and ask for a detailed final report including all data and instrument working conditions
Ask the technician to do the experiments while you are sitting nearby taking notes and learning how to switch on and off buttons depending on what you want to get
To know about the technique, the theory, the procedures, how to prepare the samples and conduct your experiment asking the technician if you have some doubts
Q 1 1: How would you best prepare a conductive sample of fine particles (e.g. a powdered metal) for routine back scattered electron imaging of the internal structure.
dust onto an adhesive carbon tab and coat with platinum
dust directly onto an Al stub and coat with carbon
stabilise in resin (e.g. epoxy), polish to a flat surface and coat with carbon
stabilise in epoxy resin, polish to a flat surface and do not coat
Q 1
2:
Approximately how long does an atom remains ionized?
Until the experiment is finished (100 seconds)
An atom that has been ionized will never gain back to its original conditions
For a very short time, in the order of 10-14 seconds
It depends which energies are involved but always in the order of 10-3 seconds
Until a neighbouring atom has an electron available to replace the ejected one
Q 1 3: A typical morphological/ topographical SEM image is generated by collecting the which electrons that come off the sample surface?
backscattered electrons
elastically scattered electrons
primary beam electrons
secondary electrons
Q 1 4: Which conditions would be most favourable for the collection of backscattered electron images from an insulating sample.
15kV primary beam, gold coated sample
15kV primary beam, carbon coated sample
3kV primary beam, gold coated sample
3kV primary beam, uncoated sample
Q 1 5: To achieve a focussed image the electron beam must be brought to a fine spot positioned at the surface of the sample. The device directly responsible for this is:
the condensor lens
the objective lens
the stigmatator coils
the scan coils
Q 1 6: When electrons interact with a solid they create an interaction volume. Which signals are produced in the interaction volume?
Auger electrons and characteristic X-rays
Characteristic X-rays and secondary electrons
Secondary electrons and Auger electrons
All of the above
Q 1
7:
Why are specimens sometimes coated with gold or platinum before microscopy?
To make the surface smoother to yield better images
To make them valuable so students will not lose them
To improve the yield of secondary electrons
To inhibit the production of backscattered electrons
Q 1 8: Once an EDS X-ray spectrum has been generated we look at the ______________ of the peaks to determine the actual elements involved.
height
width
CPS
energy
full width half maximum
Q 1
9:
What condition would result in a higher resolution backscattered electron images?
Higher acclerating voltage
Shorter working distance
Higher atomic number sample
Coating the sample
Q 2
0:
How is working distance defined in the SEM?
The seated distance between the microscopist and the microscope
The distance from the specimen to the secondary electron detector
The distance from the specimen to the objective lens pole piece
The distance from the specimen to X-ray detector
Q 2 1: What is the most likely effect that reducing the electron probe size has on a backscattered electron image?
Improve resolution
Enhance the signal-to-noise ratio
Degrade the signal-to-noise ratio
No effect
Q 2 2: What coating type is preferred for carry out energy dispersive X-ray analysis on a conducting specimen?
Gold coating
No coating
Carbon coating
Platinum coating
Q 2
3:
Starting from the top how is an SEM column organised?
a, Cathode; b, Anode; c, Whenelt cylinder; d, Condenser lens; e, Sample; f, Objective lens;
a, Cathode; b, Whenelt cylinder; c, Anode; d, Sample; e Objective lens; f Condenser lens;
a, Cathode; b, Whenelt cylinder; c, Anode; d, Condenser lens; e Objective lens; f, Sample;
a, Cathode; b, Whenelt cylinder; c, Anode; d, Objective lens; e sample; f, Condenser lens;
a, Cathode; b, Condenser lens; c, Whenelt cylinder; d, Anode; e Objective lens; f, Sample;
Q 2 4: Magnification is a direct process in an SEM. Increased magnification is the result of the sample area scanned by the beam being:
scanned more rapidly
scanned more slowly
increased in size
decreased in size
moved further from the bottom lens.
Q 2
5:
If your sample is an insulator and a carbon coating is needed the coating film should be:
Few mm thick and homogeneous to ensure sufficient contrast between sample parts having different chemical compositions
Few mm thick to ensure that sample surface will not adsorb moisture and water molecules
Few tens of nm thick and homogeneous
Few tens of nm thick and just located over the sample parts of interest
Q 2
6:
Which electron source provides the greatest brightness?
tungsten filament
LaB6 crystal
cold field emission
hot field emission
Q 2
7:
How would you prepare a finely powdered sample for secondary electron imaging?
Pour onto an aluminum specimen stub
Embed in conducting carbon tape
Glue to a glass slide
Stabilize in epoxy
Q 2
8:
Why is chilled water supplied to the scanning electron microscope?
to keep the room cool
to keep the electromagnetic lenses cool
to keep the sample cool
to keep the apertures cool
Q 2
9:
For which experiments is it essential that specimens are finely polished?
Backscattered electron imaging
Secondary electron imaging
Low vacuum electron microscopy
High resolution electron microscopy
Q 3 0: In secondary electron imaging which aspect of the sample will be dominant in determining the appearance of the image?
Density
Average atomic number
Surface roughness
All of the above
SEM Test1
Q 1: What coating type is preferred for carry out energy dispersive X-ray analysis on a conducting specimen?
Gold coating
No coating
Carbon coating
Platinum coating
Q 2: Which electron source is least appropriate for energy dispersive X-ray analysis?
Tungsten filament
LaB6
Cold field emission
Hot field emission
Q 3: The image below is of a NaCI salt crystal. What mode of imaging is most likely to have been used to generate this micrograph?
Cathodoluminescence
Backscattered electrons
Secondary electrons
Auger electrons
Q 4: What is the correct labeling for this LaB6 electron gun assembly?
A – electron emitter,
B – Wehnelt,
C – electrode
A – Wehnelt,
B – electrode emitter,
C – electrode
A – electrode,
B – Wehnelt,
C – electrode emitter
None of the above
Q 5: To achieve a focussed image the electron beam must be brought to a fine spot positioned at the surface of the sample. The device directly responsible for this is:
the condensor lens
the objective lens
the stigmatator coils
the scan coils
Q 6: For which experiments is it essential that specimens are finely polished?
Backscattered electron imaging
Secondary electron imaging
Low vacuum electron microscopy
High resolution electron microscopy
Q 7: What is the most commonly used name for the inelastic scattering process whereby primary beam electrons knock out other electrons from their shells?
Inner-shell ionization
X-ray ionization
Inner electron emission
Inner-shell X-ray emission
Q 8: Why must scanning electron microscopes operate under vacuum?
To prevent samples from degrading
To allow electrons to propagate without scattering
To prevent the electromagnetic lens from heating up
All of the above
Q 9: The interaction volumes for a variety of SEM accelerating voltages and materials are shown. Which schematic drawing represents the highest accelerating voltage and lowest average atomic number?
A
B
C
D
Q 1
If your sample is an insulator and a carbon coating is needed the coating film should be: 0:
Few mm thick and homogeneous to ensure sufficient contrast between sample parts having different chemical compositions
Few mm thick to ensure that sample surface will not adsorb moisture and water molecules
Few tens of nm thick and homogeneous
Few tens of nm thick and just located over the sample parts of interest
Q 1 1: The electron transition below will emit a characteristic X-ray. What type of transition is shown?
Kα
Kβ
L
M
Q 1 2: The high resolution secondary electron image above is of a diatom imaged at 50000X at 5mm working distance with the JSM 6400F Field emission SEM. Based on your understanding of the SEM parameters required for such images, what would be the most likely settings for the spot size and the objective lens aperture.
small diameter spot; large diameter aperture
large diameter spot; small diameter aperture
large diameter spot; large diameter aperture
small diameter spot; small diameter aperture
Q 1 3: The SEM images are generated by scanning the beam over the sample surface and collecting the signals derived from the sample-beam interactions. Where within the SEM, are you likely to find the beam scanning coils?
Immediately below the gun
Immediately below the condenser lenses
Within the objective lens
Are coupled with the anode
Q 1
4:
What type of lenses are used in the SEM column in order to focus the electron beam?
electrostatic
optical
astigmatic
electromagnetic
Q 1 5: How would you best prepare a conductive sample of fine particles (e.g. a powdered metal) for routine back scattered electron imaging of the internal structure.
dust onto an adhesive carbon tab and coat with platinum
dust directly onto an Al stub and coat with carbon
stabilise in resin (e.g. epoxy), polish to a flat surface and coat with carbon
stabilise in epoxy resin, polish to a flat surface and do not coat
Q 1 6: When a high voltage electron beam strikes a specimen, how is most of the energy dispersed?
X-rays
Heat
Secondary electrons
Backscattered electrons
Q 1
7:
What is the range of energies for Secondary Electrons?
2-50 eV
50-100 eV
0-2 eV
1000 eV
Q 1 8: What is the most likely effect that reducing the electron probe size has on a backscattered electron image?
Improve resolution
Enhance the signal-to-noise ratio
Degrade the signal-to-noise ratio
No effect
Q 1 9: For high resolution secondary electron imaging which objective lens aperture size is preferred?
Large
Medium
Small
None
Q 2 0: What is the primary reason for the scanning electron microscopes to be able to observe smaller features than an optical microscope?
Scanning electron microscopes have a superior lens system resulting in a smaller probe
The longer wavelength of electrons enable the generation of smaller probe sizes in the SEM
The shorter wavelength of electrons enable the generation of smaller probe sizes in the SEM
The specimen preparation used for SEM results in better resolution
Q 2 1: Which electrons are used to create images where contrast is proportional to average atomic number?
Absorbed electrons
Backscattered electrons
Secondary electrons
Surface electrons
Q 2
2:
What is the reason for using slow scan rates to accumulate micrographs?
The electron beam is more stable
The signal-to-noise ratio is improved
The resolution is enhanced
There is time to get a drink of water
Q 2
3:
Starting from the top how is an SEM column organised?
a, Cathode; b, Anode; c, Whenelt cylinder; d, Condenser lens; e, Sample; f, Objective lens;
a, Cathode; b, Whenelt cylinder; c, Anode; d, Sample; e Objective lens; f Condenser lens;
a, Cathode; b, Whenelt cylinder; c, Anode; d, Condenser lens; e Objective lens; f, Sample;
a, Cathode; b, Whenelt cylinder; c, Anode; d, Objective lens; e sample; f, Condenser lens;
a, Cathode; b, Condenser lens; c, Whenelt cylinder; d, Anode; e Objective lens; f, Sample;
Q 2
4:
Where inside an SEM is the Backscattered Electron Detector located?
Below the sample
All around the sample
Immediately below the objective lens
Can be inserted within the SEM column in any position
Q 2 5: Which electrons are used to create images where contrast is proportional to average atomic number?
absorbed electrons
backscattered electrons
secondary electrons
surface electrons
Q 2 6: What is the characteristic of a specimen which has been coated with a gold layer that is too thick?
It looks gold in colour
The secondary electron image is not charging
The secondary electron image is charging
The secondary electron image appears cracked or is covered by nodules
Q 2 7: In the vacuum system of a typical field emission SEM such as the JSM 6400F the typical series of vacuum pumps in the vacuum system is, starting from atmospheric pressure (air), in the order :
rotary pump; hot oil diffusion pump; ion pump
rotary pump; ion pump; hot oil diffusion pump
hot oil diffusion pump; rotary pump; ion pump
ion pump; rotary pump; hot oil diffusion pump
hot oil diffusion pump; ion pump; rotary pump
Q 2 8: 1.In most cases when X-rays pass through matter their intensity will be _________________.
unchanged
enhanced
reduced
corrected
Q 2 9: Which conditions would be most favourable for the collection of backscattered electron images from an insulating sample.
15kV primary beam, gold coated sample
15kV primary beam, carbon coated sample
3kV primary beam, gold coated sample
3kV primary beam, uncoated sample
Q 3
Why are specimens sometimes coated with gold or platinum before microscopy? 0:
To make the surface smoother to yield better images
To make them valuable so students will not lose them
To improve the yield of secondary electrons
To inhibit the production of backscattered electrons
SEM Test1
Q 1: For most elements the primary X-rays measured are formed by
_________________ ionization of the atoms that produce them.
inner shell
middle shell
outer shell
inner, middle and outer shell
Q 2: What is the correct labeling for this LaB6 electron gun assembly?
A – electron emitter,
B – Wehnelt,
C – electrode
A – Wehnelt,
B – electrode emitter,
C – electrode
A – electrode,
B – Wehnelt,
C – electrode emitter
None of the above
Q 3: In the vacuum system of a typical field emission SEM such as the JSM 6400F the typical series of vacuum pumps in the vacuum system is, starting from atmospheric pressure (air), in the order :
rotary pump; hot oil diffusion pump; ion pump
rotary pump; ion pump; hot oil diffusion pump
hot oil diffusion pump; rotary pump; ion pump
ion pump; rotary pump; hot oil diffusion pump
hot oil diffusion pump; ion pump; rotary pump
Q 4: For high resolution secondary electron imaging which objective lens aperture size is preferred?
Large
Medium
Small
None
Q 5: Why is it difficult to detect and quantify energy dispersive X-ray analyses of light elements?
Light elements volatilize easily
Light elements do not produce many X-rays
Light elements produce soft X-rays that easily absorbed
Light elements produce energetic X-rays that are highly penetrating
Q 6: Which electron source provides the greatest brightness?
tungsten filament
LaB6 crystal
cold field emission
hot field emission
Q 7: The best way to conduct experiments and get results using a SEM is?
To know about the technique, the theory, the procedures, how to prepare the samples and ask the technician to do the experiments because a scientist just need to interpret results and doesn’t need to directly conduct experiments
To know about the technique, the theory, the procedures, and ask the technician to prepare the samples because a scientist just need to interpret results and directly conduct experiments but has no time to spend preparing routine samples
Have a meeting with the technician and carefully explain him/her all the particulars of the experiment and ask for a detailed final report including all data and instrument working conditions
Ask the technician to do the experiments while you are sitting nearby taking notes and learning how to switch on and off buttons depending on what you want to get
To know about the technique, the theory, the procedures, how to prepare the samples and conduct your experiment asking the technician if you have some doubts
Q 8: The SEM images are generated by scanning the beam over the sample surface and collecting the signals derived from the sample-beam interactions. Where within the
SEM, are you likely to find the beam scanning coils?
Immediately below the gun
Immediately below the condenser lenses
Within the objective lens
Are coupled with the anode
Q 9: What is the most likely effect that reducing the electron probe size has on a backscattered electron image?
Improve resolution
Enhance the signal-to-noise ratio
Degrade the signal-to-noise ratio
No effect
Q 10 : For which material type would cold mounting be the preferred method to prepare a specimen for SEM?
For specimens with low melting points
For specimens with high melting points
For liquid samples
For magnetic materials
Q 11 : What coating type is preferred for carry out energy dispersive X-ray analysis on a conducting specimen?
Gold coating
No coating
Carbon coating
Platinum coating
Q 12
:
What type of lenses are used in the SEM column in order to focus the electron beam?
electrostatic
optical
astigmatic
electromagnetic
Q 13 : A typical morphological/ topographical SEM image is generated by collecting the which electrons that come off the sample surface?
backscattered electrons
elastically scattered electrons
primary beam electrons
secondary electrons
Q 14 : In this schematic drawing of a scanning electron microscope, which labeling scheme is correct? (1) – electron gun (2) – backscattered electron detector (3) – secondary electron detector
A = 1,
B = 2,
C = 3
A = 1,
B = 3,
C = 2
A = 2,
B = 3,
C = 1
A = 3,
B = 2,
C = 1
Q 15
:
How is working distance defined in the SEM?
The seated distance between the microscopist and the microscope
The distance from the specimen to the secondary electron detector
The distance from the specimen to the objective lens pole piece
The distance from the specimen to X-ray detector
Q 16 : When a high voltage electron beam strikes a specimen, how is most of the energy dispersed?
X-rays
Heat
Secondary electrons
Backscattered electrons
Q 17 : The picture above shows a mixed mineral sand from Dunwich that have been dusted onto an adhesive carbon tab, coated with carbon and imaged on the JSM 6460LA using one of the backscatter detector modes. Based on this data and your knowledge of compositional back scattered electron images, which is the most likely correct order for the 3 labelled particles if they are ranked from highest average atomic number to lowest atomic number.
1; 2; 3
3; 2; 1
2 ; 3, 1
1; 3; 2
3; 1; 2
Q 18 : What is the characteristic of a specimen which has been coated with a gold layer that is too thick?
It looks gold in colour
The secondary electron image is not charging
The secondary electron image is charging
The secondary electron image appears cracked or is covered by nodules
Q 19
:
Why are specimens sometimes coated with gold or platinum before microscopy?
To make the surface smoother to yield better images
To make them valuable so students will not lose them
To improve the yield of secondary electrons
To inhibit the production of backscattered electrons
Q 20 : In this secondary electron image of antimony oxides what is the most likely reason for the observed contrast?
Mixing of secondary and backscattered electron signals
Differential charging of crystal facets
Orientation dependence of secondary electron emission
All of the above
Q 21
:
For which experiments is it essential that specimens are finely polished?
Backscattered electron imaging
Secondary electron imaging
Low vacuum electron microscopy
High resolution electron microscopy
Q 22 : Which electrons are used to create images where contrast is proportional to average atomic number?
Absorbed electrons
Backscattered electrons
Secondary electrons
Surface electrons
Q 23 : What is the primary reason for the scanning electron microscopes to be able to observe smaller features than an optical microscope?
Scanning electron microscopes have a superior lens system resulting in a smaller probe
The longer wavelength of electrons enable the generation of smaller probe sizes in the SEM
The shorter wavelength of electrons enable the generation of smaller probe sizes in the SEM
The specimen preparation used for SEM results in better resolution
Q 24
:
Where inside an SEM is the Backscattered Electron Detector located?
Below the sample
All around the sample
Immediately below the objective lens
Can be inserted within the SEM column in any position
Q 25 : The image below is of a NaCI salt crystal. What mode of imaging is most likely to have been used to generate this micrograph?
Cathodoluminescence
Backscattered electrons
Secondary electrons
Auger electrons
Q 26 : What labeling scheme of the SEM shown in this photograph is correct? 1. Secondary electron detector 2. X-ray detector 3. Specimen chamber 4. OL aperture
A = 1,
B = 2,
C = 3,
D = 4
A = 1,
B = 2,
C = 4,
D = 3
A = 2,
B = 3,
C = 4,
D = 1
A = 2,
B = 4,
C = 3,
D = 1
Q 27 : Why are only secondary electrons that are near the sample surface involved in producing the secondary electrons image?
Because secondary electrons have very low energies (<50eV) and only those generated near the sample surface can escape and reach the SE detector
Because electrons near the sample surface are weakly bonded and easily ejected during the sample scanning by the electron beam
Because the electron bean can penetrate only few nanometers below the sample surface and only electrons very near the surface are emitted.
All of above
Q 28 : The electron transition below will emit a characteristic X-ray. What type of transition is shown?
Kα
Kβ
L
M
Q 29
:
What is the most commonly used name for the inelastic scattering process
whereby primary beam electrons knock out other electrons from their shells?
Inner-shell ionization
X-ray ionization
Inner electron emission
Inner-shell X-ray emission
Q 30 : How would you best prepare a dry and non-conductive sample of fine particles (e.g. talcum powder) for routine secondary electron imaging of the surface of the particles.
dust/ sprinkle onto an adhesive carbon tab and coat with platinum
dust / sprinkle directly onto a dry Al stub and do not coat
stabilise in resin (e.g. epoxy), polish to a flat surface and coat with carbon
stabilise in resin (e.g. epoxy), polish to a flat surface and coat with platinum
SEM Test1
Q 1: How would you best prepare a conductive sample of fine particles (e.g. a powdered metal) for routine back scattered electron imaging of the internal structure.
dust onto an adhesive carbon tab and coat with platinum
dust directly onto an Al stub and coat with carbon
stabilise in resin (e.g. epoxy), polish to a flat surface and coat with carbon
stabilise in epoxy resin, polish to a flat surface and do not coat
Q 2: What are correct labels for the 3 SEM filament types shown in the above image.
Field Emission Gun (FEG); b, Lanthanum hexaboride (LaB6); c, Tungsten (W) hairpin
a, Lanthanum hexaboride (LaB6); b, Field Emission Gun (FEG); c, Tungsten (W) hairpin
a, Tungsten (W) hairpin; b, Field Emission Gun (FEG); c, Lanthanum hexaboride (LaB6)
a, Tungsten (W) hairpin; b, Lanthanum hexaboride (LaB6); c, Field Emission Gun (FEG) Q 3: In secondary electron imaging which aspect of the sample will be dominant in determining the appearance of the image?
Density
Average atomic number
Surface roughness
All of the above
Q 4: The image below is of a NaCI salt crystal. What mode of imaging is most likely to have been used to generate this micrograph?
Cathodoluminescence
Backscattered electrons
Secondary electrons
Auger electrons
Q 5: Which electrons are used to create images where contrast is proportional to average atomic number?
absorbed electrons
backscattered electrons
secondary electrons
surface electrons
Q 6: How is working distance defined in the SEM?
The seated distance between the microscopist and the microscope
The distance from the specimen to the secondary electron detector
The distance from the specimen to the objective lens pole piece
The distance from the specimen to X-ray detector。