Study of the predissociation of CH3OA(2A1) by fast beam photofragment translational spectroscopy

The dissociation dynamics of the methoxy radical (CH3O) following excitation of the A(2A1) ← X(2E) transition are examined using photofragment translational spectroscopy. The radicals are produced from photodetachement of a fast, cold negative ion beam. We find that levels of the Ā state are strongly predissociated starting with ν3 = 6 at 35419 cm−1 excitation energy. Three product channels are identified: (1) CH3 + O, (2) CH2 + OH, and (3) CH2O + H, with channel (1) by far the dominant channel. In channel (1), resolved vibrational structure of the methyl fragment is seen in the translational energy distribution, providing insight into the dissociation dynamics of CH3 O. Several thermodynamics quantities are also obtained: D0(CH3O) = 87.8 ± 0.3 kcal/mol, ΔHf,00(CH3O) = 6.8 ± 0.4, D0(CH3OH) = 104.0 ± 0.5, ΔHacid,0(CH3OH) = 381.4 ± 0.7, and D0(HCH2O) = 19.8 ± 0.4.