Electron localisation: evolution of optical spectra

Abstract

Attention is directed to experiments from several groups which bear on the origin of the electron's absorption band, particularly with regard to the spontaneous progression from metastable to equilibrated states and photoinduced spectral shifts. The absorption band is discussed as being heterogeneously broadened in both solid and liquid phases, the former being space-averaged and the latter time-averaged. This means that the proper extinction coefficients are higher than those currently in use which were evaluated on the presumptioil that the band was homogeneous. E,,,, is seen as a generally useful measure of the solvating power of solvents. Chem. 55. 1987Chem. 55. (1977. Cette publication permet d'orienter I'attention vers les experiences provenant de plusieurs groupes qui ont une incidence sur I'origine des bandes dabsorption d'electrons, particulieren~ent en ce qui a trait a la progression spontanke allant d'ktats metastables vers des etats equilibrts et aux deplacements spectraux photoinduits. On discute de la bailde d'absorption comrne ktant tlargie d'une f a~o n hkterogene a la fois dans les phases solides ainsi que liquides; il se produitrait une moyenne des espaces dans les premieres et une moyenne dans le temps dans les derni6res. Ceci implique que les coefficients d'extinction appropriks sont plus hauts que ceux utilisks actuellement et qui ont kt6 evalues en faisant l'hypothese que la bande etait homogene. On considere que le E,,,, est geniralement une mesure utile du pouvoir de solvatation des solvants.[Traduit par le journal]

The role of electron–phonon interaction and non-Gaussian transport in spectral changes of trapped electrons in glasses

“…[3] leads to essentially the same result (17) as that of the usual diffusion treatment, namely, I ( t ) becomes timeindependent after a few steps.…”

“…where F,(s) is the probability that the walker reaches the origin for the first time in n steps, starting from the lattice point s. The delta function in [3] indicates that walkers reach the origin only at times which are integral multiples of the jump time r in this case. In order to generalize the flux calculation to the case of multiple-jump times, it is convenient to introduce the following generating functions,…”

A simple model for solvated electrons

“…The broadening of the spectrum has been the subject of several discussions.10, 12 The main argument in favor of a heterogeneous broadening would be a selective bleaching, due to a variety of trapping sites. Bleaching at several positions of the band for sodium-ammonia and sodiummethylamine shows homogeneous bleaching throughout the band.13 Moreover the width of the absorption spectra (ca.…”

Partial deconvolution of the absorption spectrum of trapped electrons in 15 M LiCl aqueous glasses at 77 K

“…The problem remains unsettled, however, whether there is a continuous distribution of substructures or only a small number of discrete overlapping bands contributing to the overall absorption band (5,6). A related question concerns itself with how much narrower is each individual band than the overall band (7,8).…”