Abstract
A general expression for the vibration induced intensities of transition metal ions in an octahedral environment is derived. It is found necessary to define the Y and Y′ coefficients for the octahedral group analogous to the two types of 12j coefficients in theory of angular momentum. A brief discussion of these coefficients is given together with a table of some of the more useful ones. No support is found for the view that the main contribution to the intensities comes from the 4p orbitals on the metal ion.