Detection of the Excited-State NH22A1) in the Ultraviolet Photodissociation of Methylamine

J Phys Chem A. 2016 Nov 3;120(43):8584-8589. doi: 10.1021/acs.jpca.6b08674. Epub 2016 Oct 21.

Abstract

Ion-imaging and dispersed fluorescence spectroscopy are employed for the photodissociation dynamics study of methylamine in the photolysis wavelength range 205-213 nm. The methyl radical product is found to populate a wide range of ro-vibrational states, among which the CH3 fragment generated in the v = 0 state shows a bimodal kinetic energy distribution. The internal energy analysis of the NH2 counterproduct indicates that a lower kinetic energy component, which was observed only with the CH3(v=0) fragment, energetically matches the electronically excited Ã2A1 state. The dispersed fluorescence spectrum, whose band structure is assigned to the Ã2A1 → X̃2B1 transition, provides evidence of the CH3(v=0) + NH22A1) pathway. The branching mechanism of the product pathway is discussed in terms of nuclear dynamics in the long-range region, where the conical intersection between the excited- and ground-state potential energy surfaces can play a significant role.