Microwave‐Optical Double Resonance Using Circularly Polarized Light: Spectrum of Yb3 + in CaWO4

TLDR: In this article, a double resonance technique using circularly polarized light and microwave paramagnetic resonance is described, which is applied to CaWO4: Yb3+ and definite proof that there is considerable magnetic dipole character in one of the optical transitions and very little in the others.

Abstract: A double‐resonance technique using circularly polarized light and microwave paramagnetic resonance is described. The use of the circular polarization will, in many cases, allow one to uniquely determine the representations of the states being probed. Satisfactory signal levels are obtained in most cases where Kramers doublets are being investigated. This technique is applied to CaWO4: Yb3+. Several interesting results are obtained including definite proof that there is considerable magnetic‐dipole character in one of the optical transitions and very little in the others. The satellite structure of the lines is discussed but the nature of these extra lines is still an open question.