ON THE ELECTRONIC STATES AND PHOTOCHEMISTRY OF SIMPLE ALKYL AMINES

This paper extends recent work on the excited states of methyl amine t o some other simple amines. Jet-cooled mass-resolved multiphoton ioniz ation spectroscopy is reported for methyl amine, dimethyl amine, trime thyl amine, ethyl amine, diethyl amine, and triethyl amine. A set of h igh-level calculations for methyl amine supports the assignment of S-1 as a 3s Rydberg state by predicting the experimental transition energ y to within about 1000 cm(-1) after including vibrational zero-point e nergies for each potential energy surface. Perturbations observed in t he experimental S-1<--S-0 spectrum prompt a series of calculations whi ch implicate a dissociative 3s Rydberg state in both the perturbation in the spectrum and in the photodissociation of methyl amine at these energies. A series of excited state calculations performed at the grou nd state geometry for methyl amine, dimethyl amine and trimethyl amine indicates the relative energies of the bound 3s and 3p Rydberg states as well as the first dissociative 3s Rydberg state. Taken together, t his work presents a picture of the S-1 and S-2 excited states in which dissociative low-lying Rydberg states play a significant role in both the spectroscopy and photochemistry of the simple amines. (C) 1997 Am erican Institute of Physics.