Shift of emission band upon the excitation at the long wavelength absorption edge. III. Temperature dependence of the shift and correlation with the time dependent spectral shift

Abstract

The edge-excitation red shift previously observed for quinine and related compounds has been shown to exist also for 8-anilinonaphthalene-1-sulfonic acid. The excitation energy dependent spectral shift observed here and the time dependent spectral shift observed by Chakrabarti and Ware have been interpreted satisfactorily in terms of one and the same mechanism. The previously suggested mechanism of the red shift in which the solute–solvent interaction plays an essential role is thus supported. The solvent reorientation relaxation time has been estimated from two different sets of experimental data, one concerned with the excitation energy dependent shift and the other with the time dependent shift. The estimated relaxation times are shown to be entirely different from the dielectric relaxation times of the solvent.

The red‐edge effects: 30 years of exploration

“…We call l ex * an isorelaxation point. Because of the narrow range of applied excitation wavelengths, this feature was overlooked in some earlier publications (7).…”

“…These observations were immediately confirmed and extended by another laboratory in Belarus (5) and soon Pavlovich (6) reported another unusual observation-the dependence of excitation spectra on emission wavelength. Based on the strong dependence of these effects on temperature, a connection was made between them and the extent of dielectric relaxation of the medium (7). The third laboratory in Belarus (8) performed a detailed analysis of site selectivity in excitation energy homotransfer and presented the proofs of its origin in inhomogeneous broadening of the spectra.…”

On Spectral Relaxation in Proteins†¶‖

“…One final piece of evidence for spectral relaxation in proteins is from the red edge effects. For polar fluorophores in polar viscous solvents the emission spectra shift to longer wavelengths with longer wavelength excitation (112)(113)(114)(115)(116)(117)(118)(119)(120)(121)(122). This effect is due to excitation of fluorophores that are interacting most strongly with the solvent when using excitation on the red side of the absorption.…”

An unusual red‐edge excitation and time‐dependent Stokes shift in the single tryptophan mutant protein DD‐carboxypeptidase from Streptomyces: The role of dynamics and tryptophan rotamers

“…This phenomenon was first observed some 30 yr ago in low temperature glasses and has since been called the red-edge excitation shift (REES) and variants of it (Gallay and Purkey 1970;Weber and Shinitzky 1970; Azumi 1973, 1975;Azumi et al 1976;Demchenko 1981;Lakowicz and Keating-Nakamoto 1984;Chattopadhyay and Mukherjee 1999;Chattopadhyay et al 2003). It is now well established that REES in organized assemblies, where it is most common, arises primarily because of the heterogeneity of solvation sites around the assemblies, which also contribute to inhomogeneous broadening of the absorption spectra (Klymchenko and Demchenko 2002;Mandal et al 2004 …”