Chromophor Inhomogeneity Indication by Diffuse Vibronic Spectra

Abstract

Determination of gap between optically combining states (0-0- transition) from diffuse vibronic absorption or emission spectra is possible now for homogeneous ensembles of chromophores. If the observed spectra present composite polymorphic chromophores or different species they are formed by partial spectra and differing electronic transitions. For these conditions the indicating pure-electronic transition frequency attribute is distorted, smeared or even absent. That behavior is qualitative indication of the chromophore inhomogeneity. The same would be because of impurities. It is shown that the approach of inhomogeneity qualitative indication by spectra is adaptable to different structural forms of chromophor and at polymorphic sites of containing the chromophore media. The experimental data show that the approach is applicable to see the chromophore inhomogeneity by linear and circular vibronic spectra even of molecular dye-labels. The examples of observed distortions for the spectra of different composite species in different media as manifestation of their inhomogeneity are given. As the region of indication 0-0-transition is situated at low intensity antistokes wings of spectra the sensitivity to inhomogeneity is high as to hindrance by impurities and measurement precision.