Site-dependent photodissociation of vibrationally excited CD ₃NH₂

The N-H and C-D bond fission in partially deuterated methylamine, CD ₃NH₂, has been investigated using vibrationally mediated photodissociation. Jet-cooled action spectra and Doppler profiles of the H and D photofragments were monitored following ∼243.1 nm photodissociation of the parent pre-excited to two, three or four N-H stretch quanta. The action spectra were analyzed in terms of simplified local mode/normal mode (LM/NM) and NM models, allowing band assignment and determination of the strong resonances involved in the coupling. The Doppler profiles show that the released H and D photofragments have low translational energy content and that the H is the dominant product, although its yield decreases as higher pre-excited N-H vibrational states are dissociated. The dynamics of the site-dependent bond fission in CD₃NH₂ is discussed.