Electronic and vibrational spectra of matrix isolated anthracene radical cations: Experimental and theoretical aspects
- 15 March 1993
- journal article
- research article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 98 (6) , 4494-4511
- https://doi.org/10.1063/1.465009
Abstract
Radical cations of anthracene have been formed by vapor phase electron impact followed by trapping in an argon matrix at 12 K. Visible/ultraviolet and infrared absorption spectra of the anthracene cations in an argon matrix have been run. Significant differences in the infrared band intensities between neutral and cationic anthracene have been observed. The effects of photolysis and added CCl4 have been studied and their influence on the infrared band intensities correlated with known visible bands attributable to the anthracene cation. Theoretical calculations using Pariser–Parr–Pople and intermediate neglect of differential overlap methodologies with high level multireference perturbation configuration interaction, specifically modified for spectroscopic applications, have been performed. Both approaches predict the previously observed photoelectron spectrum well. For the optical absorption, the match with the experimental spectrum is also good, but there are notable differences between the two predictions. Ab initio restricted open shell Hartree–Fock calculations for the cation vibrational frequencies show excellent correspondence with the observed infrared bands. The theoretical infrared intensities show some remarkable differences between the neutral and ionized species. For example, the CH in‐plane bending modes and CC in‐plane stretching vibrations are predicted to increase by several orders of magnitude upon ionization. Experimental infrared intensities have been estimated and certain bands do show a significant increase in the cation band intensities over the neutrals. The implication of these findings for the hypothesis that polycyclic aromatic hydrocarbon cations are responsible for the unidentified infrared emission bands from interstellar space is discussed briefly.Keywords
This publication has 54 references indexed in Scilit:
- The ultraviolet and visible spectrum of the polycyclic aromatic hydrocarbon C10H8(+) - Possible contributions to the diffuse interstellar bands and to the ultraviolet-visible extinctionThe Astrophysical Journal, 1992
- Second-order perturbation theory with a complete active space self-consistent field reference functionThe Journal of Chemical Physics, 1992
- Toward a systematic molecular orbital theory for excited statesThe Journal of Physical Chemistry, 1992
- Ionized polycyclic aromatic hydrocarbons and the diffuse interstellar bandsThe Astrophysical Journal, 1985
- Argon matrix photolysis and photoionization studies of benzene. Absorption spectrum of benzene cation and benzene dimer cationThe Journal of Chemical Physics, 1980
- Effect of Temperature on Fluorescence Quantum Yields in SolutionThe Journal of Chemical Physics, 1965
- Electron Spin Resonance Study of the Pairing Theorem for Alternant Hydrocarbons : 13C Splittings in the Anthracene Positive and Negative IonsThe Journal of Chemical Physics, 1964
- A detailed refinement of the crystal and molecular structure of anthraceneActa Crystallographica, 1956
- Quanstentheoretische Beitr ge zum BenzolproblemThe European Physical Journal A, 1931
- ber den Grundzustand des HeliumatomsThe European Physical Journal A, 1928