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Electronic spectroscopy of propadiene (allene) by electron impact

Mosher, Oren A. and Flicker, Wayne M. and Kuppermann, Aron (1975) Electronic spectroscopy of propadiene (allene) by electron impact. Journal of Chemical Physics, 62 (7). pp. 2600-2605. ISSN 0021-9606. http://resolver.caltech.edu/CaltechAUTHORS:MOSjcp75a

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Abstract

The electron impact excitation of propadiene (allene) has been studied experimentally at impact energies of 20, 40, and 60 eV and scattering angles from 6° to 80°. Two transitions with maxima at 4.28 and 4.89 eV are identified as singlet --> triplet excitations. The magnitude of the splitting between these transitions is a measure of the interaction between the two perpendicular pi molecular orbitals. The significance of these triplet excited states in the interpretation of previous electronic energy transfer experiments and sensitized photochemical studies is briefly discussed. Two very weak transitions are observed between 5.0 and 6.5 eV. The angular dependence of the corresponding cross sections indicates that these are spin-allowed but symmetry-forbidden transitions. A weak singlet --> singlet transition is seen with a maximum at 6.74 eV. This feature has also been optically observed and attributed to an electric dipole-allowed χ 1A1-->1 1E transition. This assignment is discussed in the light of the present results. The first strong transition, the χ 1A1-->1 1B2 pi-->pi* transition, appears with a maximum at 7.24 eV. Higher energy-loss features between 7.95 and 10 eV probably involve excitations to Rydberg states. A previously unreported transition to a superexcited state is observed with a maximum at 11.25 eV.


Item Type:Article
Additional Information:Copyright © 1975 American Institute of Physics. (Received 15 March 1974) Work supported in part by the United States Atomic Energy Commission Report Code CALT-767P4-128. Work performed [by O.A.M.] in partial fulfillment of the requirements for the Ph.D. degree in Chemistry at the California Institute of Technology. Amos Arthur Noyes Laboratory of Chemical Physics, Contribution No. 4842.
Record Number:CaltechAUTHORS:MOSjcp75a
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:MOSjcp75a
Alternative URL:http://dx.doi.org/10.1063/1.430843
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11010
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:22 Jun 2008
Last Modified:26 Dec 2012 10:07

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