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Vibrational branching ratios and shape resonant photoionization dynamics in N_2O

Braunstein, M. and McKoy, V. (1989) Vibrational branching ratios and shape resonant photoionization dynamics in N_2O. Journal of Chemical Physics, 90 (3). pp. 1535-1543. ISSN 0021-9606. doi:10.1063/1.456096.

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Vibrational branching ratios and photoelectron asymmetry parameters for alternative vibrational modes in the photoionization of N_2O(7σ^(−1)) have been studied using accurate photoelectron continuum orbitals. Earlier dispersed ionic fluorescence measurements [E. D. Poliakoff, M. H. Ho, M. G. White, and G. E. Leroi, Chem. Phys. Lett. 130, 91 (1986)] revealed strong non‐Franck–Condon vibrational ion distributions for both the symmetric and antisymmetric stretching modes at low photoelectron energies. Our results establish that these features arise from a σ shape resonance which, based on its dependence on internuclear geometry, must be associated with the molecular framework as a whole and not with either of its fragments, N–N or N–O. This behavior accounts for the more pronounced deviations of the vibrational branching ratios from Franck–Condon values observed in the symmetric than in the antisymmetric mode. The σ continuum also supports a second shape resonance at higher energy which does not influence the vibrational branching ratios but is quite evident in the photoelectron asymmetry parameters around a photon energy of 40 eV. These vibrationally resolved studies of the photoelectron spectra of this polyatomic system provide an interesting example of the rich shape resonant behavior that can be expected to arise in polyatomic molecules with their alternative vibrational modes.

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Additional Information:© 1989 American Institute of Physics. Received 15 September 1988; accepted 28 October 1988. This material is based upon research supported by the National Science Foundation under Grant No. CHE8521391. The authors also acknowledge use of the resources of the San Diego SuperComputer Center which is supported by the National Science Foundation. We would like to thank Dr. E. Poliakoff of Boston University and Dr. T. Perrett at the National Bureau of Standards for their helpful discussions and for making the results of their experiments available before publication. Finally, we thank Dr. A. D. McLean for providing us with SCF wave functions for N_2O at many geometries.
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Issue or Number:3
Classification Code:PACS: 33.80.Eh; 33.60.+q; 33.20.Tp
Record Number:CaltechAUTHORS:20120524-085304474
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:31626
Deposited By: Tony Diaz
Deposited On:01 Jun 2012 23:40
Last Modified:09 Nov 2021 19:57

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