Evolved Gas Analysis Using Photoionization Mass Spectrometry

Abstract

Photoionization (PI) with vacuum ultraviolet (VUV) light provides an efficient and fragmentation-free method for the soft ionization of gaseous compounds. A photoionization source with a deuterium (D2) lamp for PI was installed in a vacuum chamber in the ionization chamber of a mass spectrometer. The PI mass spectrometry (PIMS) was applied to the evolved gas analysis (EGA) system for the volatilization of organic solvents and thermal decomposition of polymers in an inert gas atmosphere. The PI mass spectrum obtained was satisfactorily characterized by only the parent ions with no contribution as a result of fragmentation during ionization. The results suggested that EGA-PIMS was an especially powerful and desirable in situ thermal analysis method for substances which evolve organic gases simultaneously and sequentially. The combination of a VUV-light source with a quadropole-mass spectrometer in EGA is described briefly, and the results compared with EGA using conventional electron impact ionization mass spectrometry are presented.