  Femtosecond spectroscopy is applied to study transient electronic and lattice
processes in bismuth. Components with relaxation times of 1 ps, 7 ps and ~ 1 ns
are detected in the photoinduced reflectivity response of the crystal. To
facilitate the assignment of the observed relaxation to the decay of particular
excited electronic states we use pump pulses with central wavelengths ranging
from 400 nm to 2.3 mum. Additionally, we examine the variation of parameters of
coherent A1g phonons upon the change of excitation and probing conditions. Data
analysis reveals a significant wavevector dependence of electron-hole and
electron- phonon coupling strength along \Gamma--T direction of the Brillouin
zone.

Materials Science;Other Condensed Matter