A mass spectrometer for studying chemical reactions

This paper describes a mass spectrometer designed to study gas-phase chemical kinetics. An ion source has been constructed which incorporates a differentially pumped, electron beam filament chamber, and line-of-sight access from the sampling pinhole to the ionization region. Experiments are described which test the effectiveness of differential pumping in reducing contamination of the sample by pyrolysis products formed from the sample on the hot filament.