Photodissociation of dimethyl sulfide at 227.5 nm:: resonance-enhanced multiphoton ionization of the methyl fragment

The photodissociation of CH3-S-CH3 following the lowest dipole-allowed transition 1 B-1(1)(9a(1) <-- 3b(1)) <-- X(1)A(1) has been studied. The CH, photofragment has been detected by 2 + 1 resonance-enhanced multiphoton ionization through the 3p(z)(2)A "(2) <-- X(2)A "(2) and 4p(z) (2)A "(2) <-- X(2)A "(2) Rydberg transitions. The vibronic spectrum corresponding to the nu(2) ,'umbrella' mode of CH3 has been measured and fragments with nu(2) = 0 to nu(2) = 4 quanta of vibrational excitation have been detected. From the analysis of the 4p(z) rotationally resolved 0(0)(0) band of CH3, rotational temperatures T-N= 325 +/- 75 K and T-K= 125 +/- 50 K have been obtained for the ground vibrational state of the nascent CH, fragment. (C) 1999 Elsevier Science B.V. All rights reserved.