Evidence of two-phonon structures is reported for some intra-configurationa
l crystal held transitions in layered V- and Cr-halides. In particular, the
crystal field spectrum of CrBr2 (3d(4)) has bean shown for the first time,
since the exciton-phonon interaction, despite its unfilled e(g) orbitals,
vanishes to first order yielding a two-phonon sequence in the (3)A(1)(G) (3)A(2)(F) band. It is suggested that the main mechanism for the occurrence
of two-phonon progressions consists in the direct coupling of the incident
photon to a two-phonon state via the second-order dipole moment operator.
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