Linewidth pressure measurement: a new technique for high vacuum characterization

Area of Science:

• Analytical Chemistry
• Physical Chemistry
• Chemical Physics

Background:

• Accurate pressure measurement is critical for quantitative ion-molecule experiments.
• Existing ionization-based methods have inherent limitations affecting accuracy.

Purpose of the Study:

• To develop and validate a novel method for precise pressure measurement in ion-molecule experiments.
• To overcome limitations associated with traditional pressure measurement techniques.

Main Methods:

• Utilizing pressure-limited Fourier transform ion cyclotron resonance (FTICR) linewidth analysis.
• Analyzing well-characterized collisions of Ar(+) with Ar to determine kinetic energy dependence.
• Employing a single-parameter fitting procedure for collision cross-section data.

Main Results:

• The FTICR linewidth method yields pressure measurements in strong agreement with cold cathode tube and electron impact ionization methods.
• The kinetic energy dependence of Ar(+)/Ar collision cross sections is accurately described by the fitting procedure.
• The new method avoids issues related to ionization potentials and pressure perturbations from electron ionization.

Conclusions:

• The FTICR linewidth analysis offers a robust and accurate alternative for pressure measurement in ion-molecule studies.
• This technique is suitable for application within the trapping cells of FTICR and Orbitrap mass spectrometers.
• Improved pressure measurement enhances the reliability of quantitative ion-molecule experiments.