Molecular dynamics of methylamine following C-H and N-H vibrational excitation and promotion to the à state

The molecular dynamics of methylamine, CH₃NH₂, was investigated via vibrationally mediated photodissociation. It was found that the ∼243.1 nm photolysis of initially excited N-H and C-H fundamental stretches and combinations and overtones of methyl deformation yields H photofragments. Surprisingly, the deformations promote the H atom release more effectively, implying mode-dependent enhancement of photodissociation in a relatively large molecule with a torsional degree of freedom. The H Doppler profiles correspond to low translational energies, supporting the dominant non-adiabatic N-H dissociation channel.