Vacuum ultraviolet photodissociation dynamics of N2O via the C-1 Pi state: The N(D-2(j=)5/2, (3/2)) + NO(X-2 Pi) product channels

We study the vacuum ultraviolet photodissociation dynamics of N2O via the C-1 Pi state by using the time-sliced velocity map ion imaging technique. Images of N(D-2(j=)5/2, (3/2)) products from the N atom elimination channels were acquired at a set of photolysis wavelengths from 142.55 to 148.19 nm. Vibrational states of the NO(X-2 Pi) co-fragments were partially resolved in experimental images. From these images, the product total kinetic energy release distributions (TKERs), branching ratios of the vibrational states of NO(X-2 Pi) co-fragments, and the vibrational state specific angular anisotropy parameters (beta) have been determined. Notable features were found in the experimental results: the TKERs show that the NO(X-2 Pi) co-fragments are highly vibrationally excited. For the highly vibrationally excited state of NO(X-2 Pi), a bimodal rotational structure is found at all the studied photolysis wavelengths. Furthermore, the vibrational state specific beta values of both spin-orbit channels (j = 3/2, 5/2) clearly show a monotonic decrease as the vibrational quantum number of NO(X-2 Pi) increases. These observations suggest that multiple dissociation pathways play a role in the formation of the N(D-2(j=)5/2, (3/2)) + NO(X-2 Pi) products: one corresponds to a fast dissociation pathway through the linear state (the C-1 Pi state) following the initial excitation to a slightly bent geometry in the vicinity of the linear C-1 Pi configuration, leading to the low rotationally excited components with relatively large beta values; the other corresponds to a relatively slow dissociation pathway through the bent C(3(1)A') or C(3(1)A '') state, leading to moderately rotationally excited NO(X-2 Pi) products with smaller beta values. Published by AIP Publishing.