Photodissociation of NO{sub 2} in the (2) {sup 2}B{sub 2} state: The O({sup 1}D{sub 2}) dissociation channel

Journal Article · Fri Aug 07 00:00:00 EDT 2009 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3194286· OSTI ID:21559760

Wilkinson, Iain; Miranda, Marcelo P. de; Whitaker, Benjamin J ^[1]

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1. School of Chemistry, University of Leeds, Leeds LS2 9JT (United Kingdom)

Direct current slice and crush velocity map imaging has been used to probe the photodissociation dynamics of nitrogen dioxide above the second dissociation limit. The paper is a companion to a previous publication [J. Chem. Phys. 128, 164318 (2008)] in which we reported results for the O({sup 3}P{sub J})+NO({sup 2}{Pi}{sub {Omega}}) adiabatic product channel. Here we examine the O({sup 1}D{sub 2})+NO({sup 2}{Pi}{sub {Omega}}) diabatic product channel at similar excitation energies. Using one- and two-color imaging experiments to observe the velocity distributions of state selected NO fragments and O atoms, respectively, we are able to build a detailed picture of the dissociation dynamics. We show that by combining the information obtained from velocity map imaging studies with mass-resolved resonantly enhanced multiphoton ionization spectroscopy it is possible to interpret and fully assign the NO images. By recording two-color images of the O({sup 1}D{sub 2}) photofragments with different polarization combinations of the pump and probe laser fields we also measure the orbital angular momentum alignment in the atomic fragment. We find that the entire O({sup 1}D{sub 2}) photofragment distribution is similarly aligned with most of the population in the M{sub J}={+-}1 magnetic sublevels. The similarity of the fragment polarizations is interpreted as a signature of all of the O({sup 1}D{sub 2}) atoms being formed via the same avoided crossing. At the photolysis energy of 5.479 52 eV we find that the NO fragments are preferentially formed in v=1 and that the vibrationally excited fragments exhibit a bimodal rotational distribution. This is in contrast to the unimodal rotational profile of the NO fragments in v=0. We discuss these observations in terms of the calculated topology of the adiabatic potential energy surfaces and attribute the vibrational inversion and rotational bimodality of the v=1 fragments to the symmetric stretch and bending motion generated on excitation to the (2) {sup 2}B{sub 2} state.

• OSTI ID: 21559760
• Journal Information: Journal of Chemical Physics, Vol. 131, Issue 5; Other Information: DOI: 10.1063/1.3194286; (c) 2009 American Institute of Physics; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATOMS
DIRECT CURRENT
DISSOCIATION
DISTRIBUTION
EXCITATION
IMAGES
LASER RADIATION
MULTI-PHOTON PROCESSES
NITRIC OXIDE
NITROGEN DIOXIDE
ORBITAL ANGULAR MOMENTUM
PHOTOIONIZATION
PHOTOLYSIS
POLARIZATION
POTENTIAL ENERGY
PROBES
ROTATIONAL STATES
SPECTROSCOPY
TOPOLOGY
VIBRATIONAL STATES
ANGULAR MOMENTUM
CHALCOGENIDES
CHEMICAL REACTIONS
CURRENTS
DECOMPOSITION
ELECTRIC CURRENTS
ELECTROMAGNETIC RADIATION
ENERGY
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
IONIZATION
MATHEMATICS
NITROGEN COMPOUNDS
NITROGEN OXIDES
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
RADIATIONS