Dynamics of Si-H vibrations in an amorphous environment

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.