Reinvestigation of the absorption and luminescence spectra of the chromium(III) complexes with iminodiacetic acid, methyliminodiacetic acid and pyridine-2,6-dicarboxylic acid

Abstract

The absorption and luminescence spectra of the title compounds have been measured at temperatures down to 5 K. In each compound the lowest energy electronic origin is identified as a relatively strong band and the vibronic origins involving the skeletal vibrations of the Cr O₄N₂ entity are the other strong bands in the spectra. The concept of a “pseudo-Stokes shift” which was introduced by other authors to explain these spectra is incorrect. Several higher energy doublet states are identified and partial vibronic analyses of some of the electronic transitions are given.