Lemaistre, J. P. and Zewail, A. H. (1980) Spin-quantization and spin-orbit coupling effects on the line shapes of triplet states. II. The "small" exciton problem. Journal of Chemical Physics, 72 (2). pp. 1055-1070. ISSN 0021-9606. http://resolver.caltech.edu/CaltechAUTHORS:20120720-085941729
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This paper presents a detailed study of the effect of spin‐quantization and spin–orbit coupling on the transition energies of triplet state dimers or small excitons. We consider both translationally equivalent (AA) and inequivalent (AB) dimers. For the AA and AB systems, we calculate transition frequency shifts induced by the spin–orbital coupling and by the spin–spin interactions between the plus (+) and minus (−) states of the dimer. As a result of these combined effects the selective coupling between the ± states of the singlet and the ± states of the triplet AA dimer system is not operative in the AB system. Furthermore, the role of the gas‐to‐crystal shifts and the intermolecular spin–spin interactions is to change the observed transition frequencies and hence cause a dispersion in the frequencies of the ± states. The relationship between such a dispersion in the AA and the same AB system is directly related to molecular parameters such as the strength of spin–orbital coupling. These results are applied to three experimental findings obtained for different dimer systems—phenazine, naphthalene, and tetrachlorobenzene dimers isolated in isotopically mixed crystals at T<2 °K. The phenazine results are reported here and the other data on naphthalene and tetrachlorobenzene were obtained from the literature. Agreement between theory and the recent experiments is encouragingly good.
|Additional Information:||© 1980 American Institute of Physics. Received 3 July 1979; accepted 24 September 1979. This work was supported in part by grant No. DMR77-19578 from the National Science Foundation, and in part by contracts from the United States Department of Energy. National Science Foundation (U.S.A.)-Centre National de la Recherche Scientifique (France). Visiting Postdoctoral Research Fellow. Alfred P. Sloan Fellow, and Camille and Henry Dreyfus Teacher-Scholar. Contribution No. 6028.|
|Subject Keywords:||L−S COUPLING, DIMERS, EXCITONS, J−J COUPLING, LINE WIDTHS, ENERGY−LEVEL TRANSITIONS, EXCITED STATES|
|Other Numbering System:|
|Classification Code:||PACS: 33.70.Jg, 31.30.-i|
|Official Citation:||Spin‐quantization and spin–orbit coupling effects on the line shapes of triplet states. II. The ‘‘small’’ exciton problem J. P. Lemaistre and A. H. Zewail J. Chem. Phys. 72, 1055 (1980); http://dx.doi.org/10.1063/1.439273|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||20 Jul 2012 16:39|
|Last Modified:||26 Dec 2012 15:38|
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