SPECTRAL INTENSITIES IN CUBIC SYSTEMS - I - PROGRESSIONS BASED UPON PARITY VIBRATIONAL-MODES

The well-resolved emission and absorption spectra of centrosymmetric c oordination compounds of the transition metal ions have been used wide ly to provide the experimental data against which to test theoretical models of vibronic intensities. With reference to the E-2(g) --> (4)A( 2g) luminescence transition, ata perfect octahedral site in Cs2SiF6, o ver than one hundred vibronic lines are observed with line widths of a few wavenumber spread over some 3000 cm(-1). This paper reports a tho rough examination of both the electronic and vibrational factors, whic h influences the observed vibronic intensities of the various assigned and identified lines in the spectra of the MnF62- complex ion in the Cs2SiF6 cubic lattice. The origin and nature of higher order vibronic interactions are analysed on the basis of a symmetrized vibronic cryst al field-ligand polarization model.