Photodissociation Dynamics of Nitrous Oxide near 145 nm: The O(1S0) and O(3P J=2,1,0) Product Channels.

ABSTRACT

We report the study of photodissociation dynamics of nitrous oxide in the vacuum ultraviolet region, using the time-sliced velocity map ion imaging technique. Ion images of the O(1S0) and O(3P J=2,1,0) products were measured at nine photolysis wavelengths from 142.55 to 148.79 nm. The product channels O(1S0) + N2(X1Σg+) and O(3P J=2,1,0) + N2(A3Σu+) have been observed. For these dissociation channels, the total kinetic energy releases of the dissociated products were acquired. With vibrational structures of the N2 coproducts partially resolved in the experimental images, the branching ratios of different vibrational states of the N2 coproducts were determined, and the vibrational state specific anisotropy parameters (ß values) were derived. Analysis shows that the O(1S0) + N2(X1Σg+) channel is primarily formed via nonadiabatic couplings between the C (1Π) state and the higher-lying D (1Σ+) state of the N2O. A moderate rotational excitation and high vibrational excitation of N2(X1Σg+) products have been observed through this pathway. On the other hand, for the O(3P J=2,1,0) + N2(A3Σu+) channels, where a slightly higher rotational excitation of N2 coproducts have been observed, the possible pathway would be via nonadiabatic couplings from the C (1Π) state to the lower-lying A(1Σ-)state.