Photoionization studies of sulfur radicals and products of their reactions.

A discharge flow-photoionization mass spectrometric system coupled to a synchrotron is employed to study intermediates and products of sulfur radical reactions related to atmospheric chemistry. Sulfur radicals are generated from reactions of oxygen or chlorine atoms with sulfur compounds in a flow tube. The gaseous reaction products are sampled into the ionization region via a three-stage differential pumping scheme. Photoionization spectra and ionization energies are measured by dispersing synchrotron radiation to ionize the samples. Using this technique, photoionization spectra and ionization energies of HSO, CH(3)SO, C(2)H(5)SO, HSCl, and some secondary reaction products, SSCl, HSSCl, HSSSH, CH(3)SOH and CH(3)SS(O)CH(3), were measured for the first time.