Vibrational dynamics of glasses at low temperatures: Investigation by single-molecule spectroscopy

The paper summarized the recent results in vibrational dynamics of disordered solids obtained in joint research of Bayreuth University and Institute of Spectroscopy RAS groups via single molecule spectroscopy (SMS). New information about microscopic parameters of the low-frequency vibrational modes (LFMs) in low-temperature glasses was obtained. Studies were based on observations of the line-broadening processes in spectra of single chromophore molecules (SMs) incorporated to disordered matrix as a local spectral probe. Solid organic system, amorphous polymer-polyisobutylene, doped with tetra-tert-butylterrylene molecules, on temperature region 1.6-40 K have been studied. The values of LFM frequencies and SM-LFM coupling constants for the LFMs in the local environment of dopand chromophores were determined. Pronounced distributions of the observed local parameters of LFMs were found. The obtained results demonstrate that SMS is an efficient tool in the study of vibrational dynamics in solid disordered systems on microscopic level.