In a recent paper [R. Coussement et al., Phys. Rev. B 45, 9755 (1992)]
it was suggested that for a long-lived state that can undergo a Mossb
auer transition, if the homogeneously broadened width, rather than the
natural width, exceeds the solid-state-induced inhomogeneous width, i
t should be possible to observe resonant emission and absorption. On t
he other hand, it is expected that the probability of absorption from
a spectral distribution of total width GAMMA should be proportional to
GAMMA(gamma)/GAMMA, where GAMMA(gamma) is the radiation width of the
absorbing nucleus. Generally GAMMA is expected to be larger than GAMMA
(gamma) because of the possibilities of internal conversion, transitio
ns between magnetic sublevels, etc., all of which contribute to homoge
neous broadening and should reduce the Mossbauer effect. The present C
omment addresses questions of principle, mathematical assumptions, and
other aspects of the work of Coussement et al. and demonstrates that
a correct statistical treatment recovers the conventional more stringe
nt requirement on the broadening.