Rsc_cp_c0cp01794a 1..6

The OH + CH3 product channel for the photodissociation of CH3OH at 157 nm was investigated using the velocity map imaging technique with the detection of CH3 radical products via (2+1) resonance-enhanced multiphoton ionization (REMPI). Images were measured for the CH3 formed in the ground and excited states (v2 = 0, 1, 2, and 3) of the umbrella vibrational mode and correlated OH vibrational state distributions were also determined. We find that the vibrational distribution of the OH fragment in the OH + CH3 channel is clearly inverted. Anisotropic distributions for the CH3 (v2 = 0, 1, 2, and 3) products were also determined, which is indicative of a fast dissociation process for the C–O bond cleavage. A slower CH3 product channel was also observed, that is assigned to a two-step photodissociation process, in which the first step is the production of a CH3O(X E) radical via the cleavage of the O–H bond in CH3OH, followed by probe laser photodissociation of the nascent CH3O radicals yielding CH3(X A1, v = 0) products.