Propensity towards H photofragments in the photodissociation of CD3NH2 pre-excited to the first N-H stretch overtone

Vibrationally mediated photodissociation combined with (2 + 1) resonantly enhanced multiphoton ionization detection of H and D photoproducts was used to assess selective bond fission in partially deuterated methylamine, CD3NH2. Jet-cooled action spectra and Doppler profiles of the H and D photofragments were obtained via 243.1 nm photodissociation of the parent containing two quanta of N-H stretch excitation. The multiband action spectra indicate that the energy flow out of the initially prepared N-H stretch to the bath states is on a picosecond time scale and that the 2v10 state (antisymmetric N-H stretch) is longer lived than the other states. Although the specificity attained by N-H stretch excitation was lost, the photofragment yield of H was nine times higher than that of D, indicating preferential N-H bond fission due to lower transition states on the excited [image omitted] state surface.