Y. Ichino et al., UNIVERSAL FEATURE OF VIBRATIONAL-MODES OF DISORDERED MATERIALS INVESTIGATED VIA OPTICAL-SPECTRA OF DOPED PROBE MOLECULES, Physica. B, Condensed matter, 220, 1996, pp. 377-379
We have experimentally determined the density of states of low-frequen
cy host vibrational modes (WDOS) which couple to the electronic states
of chromophores embedded in SiO2 and SiO2-TiO2 gels prepared by a sol
-gel method and poly(vinyl butyral). Site-selective excitation spectro
scopy has been performed at 4K to obtain the fraction of the zero-phon
on line intensity without suffering from spectral hole burning effects
. By quantitative analysis of the results, the single-site spectrum an
d the one-phonon function, which is related to WDOS, have been obtaine
d numerically. It has been found that there exists a universal feature
in normalized WDOS of chromophore-embedded amorphous solids of variou
s types.