Coherent Phonon Spectroscopy
Ultrafast optical excitation of solids suddenly turns on forces that can excite the coherent couple electron and lattice oscillations. This coherent response provides information on the . The coherent phonons oscillate approximately at frequencies of the solid under equilibrium conditions. In the presence of nonequilibrium electron-hole plasma, however, the . We follow the coherent response of semiconductors and semimetals by measuring the transient reflectivity change upon interand optical excitation. In transparent materials, such as diamond, the excitation light itself excites .
These projects are collaborations with of the National Institute for Materials Science, and of the Unversity of Tsukuba, Japan.