Photoselection Study of Charge-Transfer Complexes

Abstract

The polarization of the charge‐transfer (CT) fluorescence excited in the charge‐transfer and donor absorption band was measured for the complexes of tetracyanoethylene with benzene, toluene, ortho‐ and para‐xylene, and those of s‐trinitrobenzene and tetrachlorophthalic anhydride with anthracene in organic glass at 77°K. It was shown that (1) the fluorescence excited in the CT band is positively polarized, the degree of polarization (P) depending on the complex stability; (2) in the case of a single CT absorption band, P is independent of the wavelength of the exciting light and the case in that of a double absorption band, P is different for any subband; (3) polarization of the fluorescence excited in the donor intramolecular absorption band is negative or zero. These results are discussed on the basis of a model of a partially disoriented complex.