Photodissociation of N2O: potential energy surfaces and absorption spectrum

• Published in: The Journal of chemical physics Vol. 134; no. 6; p. 064313
• Main Author: Schinke, R
• Format: Journal Article
• Language: English
• Published: United States 14-02-2011
• Subjects: Nitrous Oxide - chemistry; Photochemical Processes; Quantum Theory; Spectrophotometry, Ultraviolet; Surface Properties
• ISSN: 1089-7690
• DOI: 10.1063/1.3553377

The ultraviolet photodissociation of N(2)O is studied by wave packet calculations using global three-dimensional potential energy surfaces for the two lowest (1)A' states. The incorporation of all internal degrees of freedom in the dynamics calculations is essential for a realistic treatment. The room-temperature absorption cross section is well reproduced, including the weak vibrational structures. Classical periodic orbits show that the latter can be attributed to large-amplitude NN stretch motion combined with strong excitation of the bend. Weakening of the NN bond toward the N + NO channel is the necessary prerequisite. The temperature dependence of the calculated cross section is significant, as expected for a dipole-forbidden transition of a linear molecule; but it is not as strong as observed experimentally [G. S. Selwyn and H. S. Johnston, J. Chem. Phys. 74, 3791 (1981)]. This shortcoming is due to an apparent underestimation of the (0,1,0) hot band absorption. On the other hand, the calculations yield reasonable predictions of the ratios of bending-state resolved absorption cross sections, σ(0, 1, 0)∕σ(0, 0, 0) and σ(0, 2, 0)∕σ(0, 0, 0), measured at 204 nm [H. Kawamata et al. J. Chem. Phys. 125, 133312 (2006)].