Electronic states of benzo[a]pyrene. Linear and magnetic circular dichroism, polarized fluorescence, and quantum chemical calculations
- Roskilde Univ. (Denmark)
- Polish Academy of Sciences, Warsaw (Poland)
- Chalmers Univ. of Technology, Gothenburg (Sweden); and others
The carcinogen benzo[a]pyrene is investigated by UV and IR linear dichroism (LD) spectroscopy in stretched polyethylene, by UV magnetic circular dichroism (MCD) spectroscopy, and by fluorescence polarization spectroscopy. The combined results lead to detailed experimental characterization of transitions in the near-UV region, with determination of polarization directions for five electronic transitions. The experimental results are compared with theoretical predictions using the PPP, CNDO/S, CNDO-SDCI, and LCOAO quantum chemical models. Excellent agreement with observed values in the low-energy region, including transition transition moment directions and MCD signs, is obtained within the LCOAO model. The theoretical analysis reveals a strong breakdown of the alternant pairing symmetry for benzo[a]pyrene, compared with those observed in the related hydrocarbons benz[a]anthracene and chrysene. 44 refs., 7 figs., 4 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 232262
- Journal Information:
- Journal of the American Chemical Society, Vol. 114, Issue 6; Other Information: PBD: 11 Mar 1992
- Country of Publication:
- United States
- Language:
- English
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