For many years the study of the Zeeman effect with various types of spectra lines has been a very successful method of investigating the electronic features of atomic structure. More recently it has proved to be a successful means of investigating some of the characteristics of atomic nuclei. Certain considerations now being brought forward, associate the fine structure of spectral lines with the spin of the nuclei of the atoms in which the radiation originates. As spectral lines with fine structure components having separations of a considerable magnitude have been found in the spectra of thallium and other elements, it is evident that in a study of the Zeeman effects for these components with magnetic fields of various strengths, a very promising filed of investigation has been created. In the investigation top be described initially to securing Zeeman effects for certain prominent lines in the spark spectrum of thallium in order to obtain information which would lead to their correct classification. While this work was in progress, other investigators, utilising the information at hand concerning the spectra of Hg I and Pb III, were able to assign classifications to a few of the wave-lengths of thallium II in question. These results are now embodied in the publication of a more extensive analysis by McLennan, McLay and Crawford (
loc. cit
.). It was thought well, however, to continue the Zeeman effect investigation having in mind either the confirmation of their classification or the extension of the information available regarding the Zeeman effect with elements of high atomic number. In general, the spectra of such atoms indicate interesting quantum vector coupling types.
Doppler-free polarization spectroscopy with a quantum cascade laser at 43 µm
