  In this paper we estimate the total cross sections for field stimulated
photoemissions and photoabsorptions by quasi-free electrons within a
non-equilibrium plasma evolving from the strong coupling to the weak coupling
regime. Such transition may occur within laser-created plasmas, when the
initially created plasma is cold but the heating of the plasma by the laser
field is efficient. In particular, such a transition may occur within plasmas
created by intense VUV radiation from a FEL as indicated by the results of the
first experiments performed at the FLASH facility at DESY.
  In order to estimate the inverse bremsstrahlung cross sections, we use
point-like and effective atomic potentials. For ions modelled as point-like
charges, the total cross sections are strongly affected by the changing plasma
environment. The maximal change of the cross sections may be of the order of 60
at the change of the plasma parameters (inverse Debye length, kappa, and the
electron density, rho_e), in the range: kappa=0-3 A^{-1} and \rho_e=0.01-1
A^{-1}. These ranges correspond to the physical conditions within the plasmas
created during the first cluster experiments performed at the FLASH facility at
DESY. In contrast, for the effective atomic potentials the total cross sections
for photoemission and photoabsorption change only by a factor of 7 at most at
the same plasma parameter range.
  Our results show that the inverse bremsstrahlung cross section estimated with
the effective atomic potentials is not much affected by the plasma environment.
This observation validates the previous estimations of the enhanced heating
effect. This is important as this effect may be responsible for high energy
absorption within clusters irradiated with VUV radiation.
