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Mass and collision cross-section determination using a low-vacuum mass spectrometer
1Departments of Environmental Sciences and Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel.
Analytical Chemistry
|June 14, 2011
Summary
A new low-vacuum mass spectrometer (LVMS) was developed for simultaneous mass and collision cross section determination. This instrument successfully measured organic ion collisions with background gases, showcasing its analytical capabilities.
Area of Science:
- Analytical Chemistry
- Physical Chemistry
- Spectroscopy
Background:
- Development of mass spectrometry techniques for operation at higher pressures.
- Need for instruments capable of simultaneous mass and collision cross section measurements.
- Challenges in ion-gas collision studies at milliTorr pressures.
Purpose of the Study:
- To develop and demonstrate a simple low-vacuum mass spectrometer (LVMS).
- To enable simultaneous determination of ion mass and collision cross sections.
- To investigate ion-molecule interactions and unimolecular ion interconversions.
Main Methods:
- Construction of a low-vacuum mass spectrometer operating in the milliTorr range.
- Utilizing time-of-flight measurements for mass resolution.
- Employing a high-gain, fast-response detector suitable for milliTorr pressures.
Main Results:
- Successful simultaneous determination of mass and collision cross sections for organic ions.
- Measurement of total collision cross sections for organic ions with He, N(2), and SF(6).
- Demonstration of the LVMS's capability to study unimolecular ion interconversions, specifically C(7)H(7)(+) to tropylium ion.
Conclusions:
- The developed LVMS is a viable instrument for studying ion-molecule collisions at milliTorr pressures.
- The system allows for simultaneous measurement of mass and collision cross sections.
- The LVMS can be applied to investigate complex ion chemistry, including structural interconversions.
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