Time resolved resonance Raman spectra of anilino radical and aniline radical cation
We report, in this paper, submicrosecond time resolved resonance Raman spectra of anilino radical and its radical cation as observed in pulse radiolytic studies of the oxidation of aniline in aqueous solution. By excitation in resonance with the broad and weak electronic transition of anilino radical at 400 nm (epsilon--1250 M/sup -1/ cm/sup -1/) we have observed, for the first time, the vibrational features of this radical. The Wilson ..nu../sub 8//sub a/ ring stretching mode at 1560 cm/sup -1/ is most strongly resonance enhanced. The ..nu../sub 7//sub a/ CN stretching band at 1505 cm/sup -1/, which is shifted to higher frequency by 231 cm/sup -1/ with respect to aniline, is also prominent. The frequency of this latter mode indicates that the CN bond in the radical has considerable double bond character. The Raman spectrum of aniline radical cation, excited in resonance with the --425 nm electronic absorption (epsilon--4000 M/sup -1/ cm/sup -1/), shows features which are similar to phenoxyl radical. Most of the observed frequencies of this radical in solution are in good agreement with vibrational energies determined by recent laser photoelectron spectroscopic studies in the vapor phase. The bands most strongly enhanced in the resonance Raman spectrum are, however, weak in the photoelectron spectrum. While the vibrational frequencies observed for anilino radical and its isoelectronic cation are quite similar, the resonance enhancement patterns are very different. In particular the ..nu../sub 14/ b/sub 2/ mode of anilino radical observed at 1324 cm/sup -1/ is highly resonance enhanced because of strong vibronic coupling between the 400 nm /sup 2/A/sub 2/--/sup 2/B/sub 1/ and the higher /sup 2/B/sub 1/--/sup 2/B/sub 1/ electronic transitions.
- Research Organization:
- Radiation Laboratory and Department of Chemistry, University of Notre Dame, Notre Dame, Indiana 46556
- OSTI ID:
- 6652787
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 86:7; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400600* -- Radiation Chemistry
ABSORPTION SPECTRA
AMINES
ANILINE
AQUEOUS SOLUTIONS
AROMATICS
ARYL RADICALS
BENZYL RADICALS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
DISPERSIONS
MIXTURES
ORGANIC COMPOUNDS
OXIDATION
RADIATION CHEMISTRY
RADIATION EFFECTS
RADICALS
RADIOLYSIS
RAMAN SPECTRA
RESONANCE
SOLUTIONS
SPECTRA