A typical XPS system operates in ultra high vacuum conditions ((UHV; P < 10−9 millibar)) Which of these samples are NOT suitable for XPS analysis at UHV?

A piece of rock with many pores

A sample which outgasses in UHV

A piece of rock with many pores

A sample which outgasses in UHV

A solid polymer which is stable under x-rays in UHV

Nanoparticles on a conductive substrate

A well resolved Si2p spectrum of pure silicon has two peaks. Why is this?

Each peak represents an electron with a different angular momentum from the 2p subshell.

Each peak represents a chemical state, and it has two chemical states

Each peak represents an electron with a different angular momentum from the 2p subshell.

There is overlap with the adventitious carbon peak which is present with ALL samples.

The sample drifted during analysis

RMMF XPS Online Quiz

1.

Most samples that have been exposed to the atmosphere will have a detectable quantity of adventitious carbon contamination. (Typically with a layer thickness of 1-2 nm). What is the binding energy of the C1s peak for this adventitious carbon?
- A.
  
  284.8 eV
- B.
  
  285 keV
- C.
  
  292 eV
- D.
  
  1220 eV
Correct Answer
A. 284.8 eV

Explanation
Visit https://xpssimplified.com/ for binding energies of subshell electrons.

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2.

XPS is achieved by firing an X-ray beam at a sample, and then measuring the kinetic energy of the emitted electrons. How deep are these measured electrons coming from?
- A.
  
  1 - 20 nm
- B.
  
  1 - 20 microns
- C.
  
  1 - 20 angstroms
- D.
  
  1 - 20 mm
Correct Answer
A. 1 - 20 nm

Explanation
Though the X-rays penetrate quite deep, it is the near surface electrons which have enough kinetic energy to get to the detector which are analysed in XPS.

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3.

Which of the following peaks would represent Auger electron emission?
- A.
  
  O KLL
- B.
  
  Ba MNN
- C.
  
  Ba 3d
- D.
  
  O1s
Correct Answer(s)
A. O KLL
B. Ba MNN

Explanation
Auger electron emission occurs when an electron from a higher energy level fills the hole left by an ejected core electron, resulting in the emission of an Auger electron. In this case, both O KLL and Ba MNN represent core-level electron transitions, where an electron from a higher energy level fills a core-level hole. Therefore, both O KLL and Ba MNN peaks could potentially represent Auger electron emission. The other options, Ba 3d and O1s, do not involve core-level electron transitions and are not relevant to Auger electron emission.

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4.

What is the energy (in eV) of the aluminium K-alpha x-rays used for analysis in the Thermo K-Alpha XPS system used in the RMMF?

Correct Answer(s)
1486.7, 1486.7eV, 1486.7 eV

Explanation
The energy of the aluminium K-alpha x-rays used for analysis in the Thermo K-Alpha XPS system used in the RMMF is 1486.7 eV.

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5.

After excitation from the x-rays, photoemission occurs, ejecting electrons from the sample with a variety of energies (forming an XPS spectrum). What energy of the electrons is being directly measured by the spectrometer?
- A.
  
  Kinetic energy
- B.
  
  Binding energy
- C.
  
  Thermal energy
Correct Answer
A. Kinetic energy

Explanation
The spectrometer directly measures the kinetic energy of the electrons that are ejected from the sample after being excited by x-rays. This is because the kinetic energy of the electrons is directly related to their velocity and can be measured by analyzing their motion in the spectrometer. Binding energy refers to the energy required to remove an electron from an atom, while thermal energy is the energy associated with the random motion of particles in a sample.

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6.

XPS is a good technique for measuring the atomic concentration of a bulk sample
- A.
  
  True
- B.
  
  False
Correct Answer
B. False

Explanation
XPS, or X-ray photoelectron spectroscopy, is not a suitable technique for measuring the atomic concentration of a bulk sample. XPS is primarily used to analyze the surface composition and chemical state of materials. It provides information about the elements present on the surface and their chemical bonding, but it does not provide quantitative measurements of atomic concentration throughout the bulk of a sample. Other techniques, such as Auger electron spectroscopy or energy-dispersive X-ray spectroscopy, are better suited for determining atomic concentration in bulk samples.

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7.

What possible methods could be used to improve the signal/noise ratio of your XPS spectrum?
- A.
  
  Take more scans
- B.
  
  Increase scan dwell time
- C.
  
  Increase the pass energy
- D.
  
  Increase the spot size
- E.
  
  All of the above
Correct Answer
E. All of the above

Explanation
To improve the signal/noise ratio of the XPS spectrum, multiple methods can be used. Taking more scans increases the amount of data collected, which can help to enhance the signal and reduce the noise. Increasing the scan dwell time allows for a longer integration time, resulting in a stronger signal. Increasing the pass energy can improve the resolution of the spectrum, making it easier to distinguish between the signal and noise. Lastly, increasing the spot size can provide a larger area for data collection, increasing the overall signal strength. Therefore, all of the mentioned methods can be used to improve the signal/noise ratio of the XPS spectrum.

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8.

A typical XPS system operates in ultra high vacuum conditions ((UHV; P < 10⁻⁹ millibar)) Which of these samples are NOT suitable for XPS analysis at UHV?
- A.
  
  A piece of rock with many pores
- B.
  
  A thin continuous metal film
- C.
  
  A sample which contains water
- D.
  
  A sample which outgasses in UHV
- E.
  
  A solid polymer which is stable under x-rays in UHV
- F.
  
  A monomer sample
- G.
  
  Nanoparticles on a conductive substrate
- H.
  
  A non-conductive sample
Correct Answer(s)
A. A piece of rock with many pores
C. A sample which contains water
D. A sample which outgasses in UHV
F. A monomer sample

Explanation
XPS analysis requires ultra high vacuum conditions, which means that any sample that can release gas or contain moisture is not suitable for analysis. A piece of rock with many pores can release gas, a sample containing water can introduce moisture, a sample that outgasses in UHV can release gas, and a monomer sample can also release gas. Therefore, these samples are not suitable for XPS analysis at UHV.

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9.

A well resolved Si2p spectrum of pure silicon has two peaks. Why is this?
- A.
  
  Each peak represents a chemical state, and it has two chemical states
- B.
  
  Each peak represents an electron with a different angular momentum from the 2p subshell.
- C.
  
  There is overlap with the adventitious carbon peak which is present with ALL samples.
- D.
  
  The sample drifted during analysis
Correct Answer
B. Each peak represents an electron with a different angular momentum from the 2p subshell.

Rmmf XPS Online Quiz

Most samples that have been exposed to the atmosphere will have a detectable quantity of adventitious carbon contamination. (Typically with a layer thickness of 1-2 nm). What is the binding energy of the C1s peak for this adventitious carbon?

XPS is achieved by firing an X-ray beam at a sample, and then measuring the kinetic energy of the emitted electrons. How deep are these measured electrons coming from?

Which of the following peaks would represent Auger electron emission?

What is the energy (in eV) of the aluminium K-alpha x-rays used for analysis in the Thermo K-Alpha XPS system used in the RMMF?

After excitation from the x-rays, photoemission occurs, ejecting electrons from the sample with a variety of energies (forming an XPS spectrum). What energy of the electrons is being directly measured by the spectrometer?

XPS is a good technique for measuring the atomic concentration of a bulk sample

What possible methods could be used to improve the signal/noise ratio of your XPS spectrum?

A typical XPS system operates in ultra high vacuum conditions ((UHV; P < 10−9 millibar)) Which of these samples are NOT suitable for XPS analysis at UHV?

A well resolved Si2p spectrum of pure silicon has two peaks. Why is this?

A typical XPS system operates in ultra high vacuum conditions ((UHV; P < 10⁻⁹ millibar)) Which of these samples are NOT suitable for XPS analysis at UHV?