Frequency Dependence of the Quadratic Electron-Phonon Coupling Constant in a Polymer Glass: Direct Measurement by Single-Molecule Spectroscopy

Andrei V. Naumov, Yury G. Vainer, Lothar Kador

2009, in: Physical Review B Phys. Rev. B (2009) Bd.:79 Hnr.: 13 S.: 132201-1 - 132201-4

Abstract:
The frequency dependence of the quadratic coupling constant between the electron system of the chromophores and the quasilocal vibrational modes of the matrix, B(omega0) and its distribution was measured in a disordered system via single-molecule spectroscopy. A correlation between B and omega0 was found which does not follow a power law. The analysis of this result allows us to suggest that, for a correct description of the broadening of optical impurity spectra in disordered solids, the applicability of the weak-coupling limit and the long-wavelength approximation should be considered separately for each single molecule interacting with its local environment. A simple formulation of the electron-phonon coupling theory for the dye-matrix system as a whole is, in general, not appropriate.