Spectroscopy in Inorganic Chemistry

The recording and interpretation of electronic molecular spectra of transition-metal compounds started in earnest about 1950. Thanks to the easy operation of recording spectrophotometers and the relative ease with which crystal field level diagrams can be constructed, the number of papers dealing with absorption spectra and their interpretations is by now very large indeed. Most of these spectra have been obtained from solutions. However, more and more it has been realized that the spectra of crystals containing transition-metal ions are of greater value than solution spectra. In fact, a recent review paper (52), which dealt solely with crystal spectra and which did not aim at completeness, contained 215 pages and 460 references! The total number of references to solution spectra would now probably run to 20,000. To review such a gross number of papers is probably not possible and certainly not desirable.