A. Melikyan et al., On the theory of relaxation of electrons excited by femtosecond laser pulses in thin metallic films, APP PHYS B, 68(3), 1999, pp. 411-414
We develop a theory of electron-phonon interactions in thin metallic films
in order to explain the behavior of the carrier relaxation rate with film t
hickness. In the theoretical approach presented here we take into account t
he quantization of the phonon spectrum which is a result of phonon confinem
ent. The main consequences of the quantization of the phonon spectrum are:
(1) the existence of a nonzero lower limit of acoustic phonon frequency and
wave vector, and (2) kinematic restrictions following from the energy and
momentum conservation laws. We conclude that these consequences reduce the
available region of phase space of electron-phonon scattering probability.