An evolved gas analysis method for the characterization of sulfur vapor

In this study, thermal analysis coupled with soft ionization mass spectrometry was used for the speciation of sulfur vapor. Its investigation is still a challenge, since it exhibits a complex molecular composition. A thermal analysis–mass spectrometry system was equipped with a single-photon ionization time-of-flight mass spectrometer. Single-photon ionization is a soft ionization method which produces less or no fragments. Ionization is performed with vacuum ultraviolet photons generated by an electron beam-pumped excimer lamp and a deuterium lamp. The applicability of the developed system was demonstrated for the determination of sulfur vapor composition. Several allotropic modifications were detected in the gas phase depending on temperature. Since the ionization energies of the species are between 8.6 and 9.7 eV, soft ionization is crucial for this reason. Thermogravimetric and DSC data deliver additional information to the mass spectrometric data and enable the detection of allotropic transitions in solid and liquid phase.