Vacuum ultraviolet photodissociation dynamics of methanol at 121.6 nm

Vacuum ultraviolet (VUV) photodissociation of CH3OH and CH3OD at 121.6 nm was studied using high-n Rydberg atom time-of-flight (HRTOF) technique. The H-atom product TOF spectrum of CH3OH and D-atom spectrum of CH3OD have bimodal distributions. O–H (CH3O + H(D)) and C–H (CH2OH(D) + H) dissociations contribute to the fast component. The slow component corresponds to CH2O + H + H(D) production, mainly from three-body photodissociation, plus small contributions from secondary dissociation of CH3O and CH2OH(D). The CH2O + H + H formation is the major photodissociation pathway, with a branching ratio of (CH2O + H + H):(CH3O + H):(CH2OH + H) ≈ 1:0.25:0.15.