Two-photon-induced fluorescence.
Nonresonant two-photon electronic spectroscopy of polyatomic molecules is reviewed for the period since 1979. Emphasis is placed on studies that expose patterns in the two-photon fluorescence (also ionization, optoacoustic) excitation spectra of aromatic hydrocarbons and the effect of vibrations and substitution, particularly within the framework of pseudoparity rules. A section is devoted to biological molecules and the emerging use of two-photon-induced fluorescence anisotropy. Relevant theoretical results are discussed, with emphasis on quantum chemical predictions of vibronic coupling and substituent effects on two-photon absorptivity and tensor properties of individual molecules. This chapter includes higher-order spectroscopy, and a limited number of three- and four-photon studies are discussed.
Callis
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PR
Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA. callis@chemistry.montana.edu