Parametrization of rare-earth ion transition intensities

Abstract

A new parametrization is proposed which enables the intensities of transitions between crystal field split levels to be related to parameters representing the components of a vector field. Unlike the conventional parameters which are related to the odd parity components of the crystal field coupling the 4f to the nd and ng excited states, the new parameters are defined in a way which is explicitly independent of the physical processes involved. Use of these parameters enables the authors to explain a paradox in the interpretation of the odd parity crystal field.