LIGAND-FRAMEWORK COUPLING VIBRATIONS. THE 2Eg -> 4A2g TRANSITION IN THE Cr(CN)63- COMPLEX ION

R. Acevedoa, M. Passmanb and G. Navarroc aFacultad de Ciencias Fisicas y Matematicas, Universidad de Chile Beaucheff 850, Casilla, 2777, Santiago, Chile bLaser Laboratory, School of Biology and Chemical Sciences Birkbeck College, University of London Gordon House, 29, Gordon Square, London, WC1H-0PP, UK cComision Chilena de Energia Nuclear, Amunategui 95, Casilla, 188-D, Santiago, Chile

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Received: April 20, 2000; revised version December 27, 2000

In this research paper we examine the role played by the bending vibrational modes of motion, δ(Cr-C-N) to influence the observed overall and relative vibronic intensity distribution for the 2Eg -> 4A2g phosphorescence of the Cr(CN)63- complex ion. The calculation was carried out assuming both: (a)~a~seven-atom system model (molecular approximation) and (b)~a~negligible distortion from the octahedral symmetry for the system. The ligand polarization formalism was employed with reference to this system, since the ligand subsystems (CN)-1 are highly polarizable and as a consequence a conventional crystal field calculation would be both unrealistic and unappropriate. This system was chosen since there is a solid evidence to conclude that vibrations of the same type in the τ1u and τ2u symmetry blocks induce comparable intensity. This is a clear indication that both the τ1u and τ2u: δ(Cr-C-N) bending vibrations are exceptionally efficient to promote this radiative transition. This dynamical model is tested against the experimental data and it is shown that the model calculation, though approximate, gives results in excellent agreement with experiment.

DOI: 10.12693/APhysPolA.99.215 PACS numbers: 32.70.Fw, 32.70.Cs