Numerical Simulation and Experimental Study of a Dual-Ionization Source (PI/EI) Quadrupole Mass Spectrometer Based on...

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Chemical Instrumentation

Background:

• Traditional electron ionization (EI) causes spectral congestion in complex gas mixture analysis due to extensive fragmentation.
• Photoionization (PI) offers cleaner spectra by preserving molecular ions but has limited selectivity for low ionization energy species.
• Existing methods struggle with comprehensive detection of diverse gas mixtures.

Purpose of the Study:

• To develop a novel dual-ionization source quadrupole mass spectrometer (DISQMS) integrating PI and EI.
• To optimize instrument design and sensitivity using multiphysics ion trajectory simulations.
• To enable simultaneous comprehensive and detailed analysis of complex gas mixtures.

Main Methods:

• Developed a DISQMS integrating both PI and EI capabilities.
• Employed multiphysics ion trajectory simulations (CFD-DSMC coupled with electric fields) for design and optimization.
• Experimentally validated simulation models and optimized key instrumental parameters.

Main Results:

• Achieved clean organic spectra using PI mode for compounds like acetone and benzene.
• Obtained comprehensive detection of inorganic gases (N2, O2) with high ionization energies using EI mode.
• Acquired detailed fragment-ion information in EI mode, complementing PI's molecular ion data.

Conclusions:

• Successfully developed and validated a DISQMS with dual-mode ionization.
• Demonstrated complementary detection of organic and inorganic species.
• Facilitated spectral interpretation and molecular structure elucidation by combining EI and PI data.