A study of the S(3P2,1,0;1D2) production in the 193 nm photodissociation of CH3S(X̃)

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Abstract
The dynamics of S(3 P 2,1,0;1 D 2) production from the 193 nm photodissociation of CH3SCH3 has been studied using 2+1 resonance‐enhanced multiphoton ionization techniques. The 193 nm photodissociation cross section for the formation of S from CH3S initially prepared in the photodissociation of CH3SCH3 is estimated to be 1×10−18 cm2. The branching ratio for S(3 P)/S(1 D) is found to be 0.15/0.85. The fine‐structure distribution observed for product S(3 P 2,1,0) is nearly statistical. Possible potential energy surfaces involved in the 193 nm photodissociation of CH3S(X̃) have been examined theoretically along the CH3–S dissociation coordinate in C 3v symmetry. These calculations suggest that predissociation of CH3S(C̃ 2 A 2) via the repulsive CH3S(Ẽ 2 E) surface is most likely responsible for the efficient production of S(1 D). For vibrationally excited CH3S(X̃), a viable mechanism for the dominant production of S(1 D) may involve direct dissociation via the CH3S(Ẽ 2 E) state formed in the 193 nm photoexcitation.