Abstract
Infrared transient grating measurements on the stretch mode at in hydrogenated amorphous germanium show a long, multiexponential relaxation time having a mean decay constant of . The thermal activation of the decay rate suggests a decay via two bending modes with the energy mismatch bridged by three bulk vibrations. From the probe pulse diffraction efficiency, we have determined a value for the nonlinear refractive index of . Utilizing the photon echo technique, we determine that the dominant contribution to a vibrational dephasing near room temperature is the elastic scattering of TO modes near . At additional dephasing from nonequilibrium phonons are readily observable as an excitation dependent contribution.
- Received 4 October 2005
DOI:https://doi.org/10.1103/PhysRevB.73.155202
©2006 American Physical Society