Photoionization study of CH3SCH2Cl formed in the reaction system Cl/Cl-2/CH3SCH3

A photoionization-efficiency spectrum of CH3SCH2Cl was measured over the wa velength range 108-142 nm by means of a photoionization mass spectrometer c oupled to a synchrotron as the source of radiation. Gaseous CH3SCH2Cl was g enerated in a discharge-flow reactor involving Cl, Cl-2, and CH3SCH3 at roo m temperature via these sequential reactions: Cl + CH3SCH3--> CH3SCH2 + HCl ; CH3SCH2 + Cl-2--> CH3SCH2Cl + Cl. According to the PIE spectrum of CH3SCH 2Cl thus obtained, the ionization energy is (9.077 +/-0.007) eV. Based on G AUSSIAN-2 calculations, the observed ionization of CH3SCH2Cl near the thres hold region is likely to form from singlet CH3SCH2Cl ionizing to doublet CH 3SCH2Cl+; the calculated ionization energy 9.064 eV agrees with the experim ental value. The adiabatic ionization energy of CH3SCH2 and appearance ener gy of CH3SCH2+ from CH3SCH2Cl were determined to be (6.884 +/-0.008) eV and (10.007 +/-0.016) eV, respectively; the dissociation energy of the CH3SCH2 -Cl bond is thus derived to be (72.0 +/-0.6) kcal mol(-1). (C) 2001 America n Institute of Physics.