VUV Photodissociation Dynamics of Nitrous Oxide: The O((1)SJ=0) and O((3)PJ=2,1,0) Product Channels.

Abstract

Vacuum ultraviolet photodissociation dynamics of nitrous oxide was investigated using the time-sliced velocity ion imaging technique. Images of the O((1)SJ=0) and the O((3)PJ=2,1,0) products were measured at nine photolysis wavelengths from 124.44 to 133.20 nm, respectively. Three main dissociation channels: O((1)S0) + N2(X(1)Σg(+)), O((3)PJ=2,1,0) + N2(A(3)Σu(+)), and O((3)PJ=2,1,0) + N2(B(3)Πg) were observed and identified in the product images where vibrational states of N2 were fully resolved. Product total kinetic energy releases and angular distributions were acquired. In all product channels, the branching ratios of vibrational states of N2 products were determined. In addition, the O((3)PJ=2,1,0) + N2(A(3)Σu(+))/O((3)PJ=2,1,0) + N2(B(3)Πg) branching ratios were determined. We found that in the O((3)PJ=2,1,0) channels the O((3)PJ=2,1,0) + N2(B(3)Πg) channel becomes dominant at long photolysis wavelength, indicating a strong coupling between the singlet D((1)Σg(+)) state and the triplet (3)Π state. For both O((1)S0) and O((3)PJ=2,1,0) products, the derived angular anisotropy parameters (β values) are very close to 2 at lower vibrational states of the correlated N2 electronic states and gradually decrease with the increasing vibrational quantum number. These behaviors suggest that the photodissociation processes are primarily governed by a fast dissociation in a linear geometry, while the N2 products at excited vibrational states are very likely produced via a more bent transition state.