  Spectral and kinetic properties of extrinsic crossluminescence (CL) in
SrF2:Ba(1%) and CaF2:Ba(1%) are compared with those of intrinsic CL in BaF2 and
are analyzed taking into account EXAFS data obtained at the Ba LIII edge and
results of first-principles calculations. The CL decay time was revealed to be
longer in SrF2:Ba and CaF2:Ba compared to BaF2. This fact contradicts the
expected acceleration of luminescence decay which could result from an
increased overlap of wave functions in solid solutions due to shortening of the
Ba-F distance obtained in both EXAFS measurements and first-principles
calculations. This discrepancy is explained by the effect of migration and
subsequent non-radiative decay of the Ba(5p) core holes in BaF2 and by
decreasing of the probability of optical transitions between Ba(5p) states and
the valence band in SrF2:Ba and CaF2:Ba predicted by first-principles
calculations.
