We present results of the first vibrational photon-echo, transient-grating, and temperature dependent transient-bleaching experiments on a-Si:H. Using these techniques, and the infrared light of a free electron laser, the vibrational population decay and phase relaxation of the Si-H stretching mode were investigated. Careful analysis of the data indicates that the vibrational energy relaxes directly into Si-H bending modes and Si phonons, with a distribution of rates determined by the amorphous host. Conversely, the pure dephasing appears to be single exponential, and can be modeled by dephasing via two-phonon interactions.

Phys. Rev. Lett.

van der Voort, M., Rella, C. W., van der Meer, L. F. G., Akimov, A. V., & Dijkhuis, J. I. (2000). Dynamics of Si-H vibrations in an amorphous environment. Phys.Rev.Lett., 84, 1236–1239.