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 1B1(9a1←3b1)←X 1A1 has been studied. The CH3 photofragment has been detected by 2+1 resonance-enhanced multiphoton ionization through the 3pz 2A2′′←X 2A2′′ and 4pz 2A2′′←X 2A2′′ Rydberg transitions. The vibronic spectrum corresponding to the ν2 `umbrellaʹ mode of CH3 has been measured and fragments with ν2=0 to ν2=4 quanta of vibrational excitation have been detected. From the analysis of the 4pz rotationally resolved 000 band of CH3, rotational temperatures TN=325±75 K and TK=125±50 K have been obtained for the ground vibrational state of the nascent CH3 fragment.