Secondary ions entering a mass filter in Secondary Ion Mass Sprectrometry (SIMS)

In summary, Secondary Ion Mass Spectrometry (SIMS) uses a mass filter to sort out secondary ions based on their mass/charge ratio. Different types of mass filters, such as quadrupole, magnetic sector, and time-of-flight (TOF), are used in SIMS. In TOF, the secondary ions are accelerated before entering the flight tube to ensure they have the same kinetic energy. In magnetic sector filters, the separation of ions follows a specific equation. However, there may be variations in the energy of secondary ions during sputtering, which can be addressed by devices such as the reflectron in TOF SIMS. Further information on this topic can be found in the link provided.
  • #1
Deleted member 655103
Hello,
I have a question about secondary ions entering a mass filter in Secondary Ion Mass Sprectrometry (SIMS).
We know that secondary ions are sputtered from surface of studied sample. Those secondary ions are entering a mass filter which sort them out due to their mass/charge ratio. After that they enter a deterctor.
We use quadrupole mass filters, magnetic sector filters or time-of-flight filters.
In TOF, separation of secondary ions (due to m/q ratio) follows the equation:
6e99d3b829cff9cc1d21200227a992d79d16fff6

In magnetic sector filters separation follows the equation:
2a9168ed4f7208ae94e0518561ed71166491b48a

MY QUESTION: All ions should enter the mass filter with the same energy at the same time. How is it done (we know that some secondary ions gain more energy some secondary ions gain less energy during sputtering)?
I know that TOF uses device called reflectron to this purpose but how about magnetic sector filters?
Could you please post a link to some good article explaining this problem.
Thanks a lot!
 
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  • #2
epsilonpi said:
All ions should enter the mass filter with the same energy at the same time.

Regarding TOF-SIMS: Before entering the "flight tube", the secondary ions are accelerated using a strong electric field so that they all have approximately the same kinetic energy.
[PDF]
TOF MS intro - Chemie Unibas
 
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  • #3

1. How do secondary ions enter the mass filter in SIMS?

Secondary ions are produced from the sample surface by a primary ion beam. These ions are then accelerated and focused towards the mass filter by an electric field. The mass filter allows only ions with a specific mass-to-charge ratio to pass through, while all other ions are filtered out.

2. What is the purpose of the mass filter in SIMS?

The mass filter is used to separate and filter out secondary ions based on their mass-to-charge ratio. This allows for the detection of specific elements and isotopes within the sample, providing valuable information about its composition and structure.

3. How does the mass filter work in SIMS?

The mass filter uses a combination of electric and magnetic fields to separate ions based on their mass-to-charge ratio. The electric field accelerates the ions towards the filter, while the magnetic field deflects them based on their mass-to-charge ratio. Only ions with the desired mass-to-charge ratio are able to pass through and reach the detector.

4. Can the mass filter in SIMS be adjusted for different mass ranges?

Yes, the mass filter can be adjusted to filter out ions within a specific mass range. This can be done by adjusting the strength of the electric and magnetic fields, as well as the shape and positioning of the filter. This allows for a more targeted analysis of specific elements and isotopes within the sample.

5. Are there any limitations to the mass filter in SIMS?

While the mass filter is a powerful tool in SIMS, it does have limitations. It may not be able to distinguish between ions with very similar mass-to-charge ratios, leading to potential errors in the analysis. Additionally, the mass filter may not be able to filter out all unwanted ions, which can affect the accuracy of the results.

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