The effect of pressure on the optical charge-transfer (CT) band of the ion pair [Fe(CN)6]-4·DMV2+ (DMV = dimethyl viologen) has been studied in aqueous solution. In the pressure range 0.001 to 10.0 kbar the CT band maximum shifted to higher energy by ≈1700 cm-1 and the integrated intensity of the CT band increased by ≈35%, with no change in the peak width. These results accord with a vibronic coupling model describe to mixed-valence metal compounds, with a general theory of absorption spectra of ions in solution, as well as with Mulliken's theory of charge transfer. The oscillator strength of the CT band decreased by over a factor of 2 at ambient pressure with increasing concentration of the ion pair (from 1.0 to 50 mM), correlating with the change of the ionic strength over this concentration range.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry