The Zeeman effect in molecular doublet-doublet transitions in the " high field-low field " limit

2014 Zeeman line profiles for spin-allowed and forbidden electronic doublet-doublet transitions of molecular asymmetric tops have been computed for the case in which one of the combining states has a much larger zero-field splitting than the other. In such cases there must exist a range of external fields which are weak with respect to the high zero-field splitting state and strong with respect to the low zero-field splitting state. The respective Zeeman effects are therefore close to the weak-field limit of a strongly coupled state and the strong-field, uncoupled limit (Paschen-Back effect) of the weakly coupled state. Zeeman component frequencies and intensities have been calculated for this « high field-low field » limit, and Zeeman pattern profiles of lines are seen to depend mostly on branch selection rules. Lines with 0394N = 0394J show a central maximum, whereas lines with 0394N = 0394J ± 1 exhibit a saddle shape, regardless of light polarization. The former type of lines occurs in spin-allowed transitions, the latter in the 0394N = ± 2 branches of spin-forbidden transitions. The two types of shape are mixed together in the remaining branches of spin-forbidden transitions. J. Physique LETTRES 43 (1982) L-383 L-387 ler JUIN 1982, Classification Physics Abstracts 33.10