Magnetic Dichroism in the Vacuum Ultraviolet

The purpose of this work is to highlight two recent developments in absorption dichroism studies. The first of these, the SDI, permits the simultaneous measurement of linear, elliptical and circular dichroism spectra and, also simultaneously, absorption spectra. It is unaffected by the non-sinusoidal nature of the periodic signals, by large changes of optical density or by voltage feedback restrictions. It should simplify experiment and, by virtue of larger resolution and fidelity, it should do much to increase the quality of the results. The second development was occasioned by the frustration of the authors when confronted by MCD signatures that were not of a classical type. A modeling technique has been developed that can handle contrary signatures, and it has performed well on three of the first Rydberg transitions of HI, two of them very non-classical. It is true that roelectronic assignments were already available for these three transitions and that the simulations merely verify those prior assignments. However, confrontation by a signature for which the corresponding transition is unassigned should present no difficulty other than considerably more work and, if the signature be adequately unique, it should provide rather incontrovertible assignments.