Vibrational IR‐Multiphoton Excitation of Thiirane‐1‐oxide (C2H4SO) and d‐Thiirane‐1‐oxide (C2H3DSO)

Abstract

AbstractWe report the IR‐laser‐induced dissociation of C2H4SO and of C2H3DSO, which was synthesized for the first time. After multiphoton excitation in the frequency range of the SO chromophore (with a large band strength of G = 2.4 pm2 for C2H4SO and 2.8 pm2 for C2H3DSO) in the 1060‐1090 cm−1 range of the CO2 laser the product analysis was carried out by static yield measurements using quantitative IR‐spectroscopy of ethylene (C2H3D, C2H4). Effective laser chemical rate constants k1(st) = (0.70±0.38) cm2 J−1 for C2H3DSO with excitation at v̄(R28) = 1083.48 cm−1 and (0.52±0.14) cm2 J−1 for C2H4SO were obtained from a fit to the fluence dependence of the photochemical primary yields. A nonlinear intensity dependence of the apparent product yield (Papp) was found by using different temporal pulse profiles (singlemode, mode‐locked and multimode pulses) at 1083.48 cm−1 (9R28) for C2H4SO and at 1082.30 cm−1 (9R26) for C2H3DSO in static yield measurements and time‐resolved experiments. FTIR measurements were performed to assign the fundamentals of C2H3DSO, which are compared with the harmonic frequencies calculated using GAUSSIAN 92 at MP2 level with different basis sets.