AUGER-ELECTRON SPECTROSCOPY OF MOLECULES - THEORY FOR SPIN POLARIZATION FOLLOWING PHOTOABSORPTION

In this article we derive an expression for the angular distribution of spin-detected electrons emitted in the Auger decay of a vacancy created by photoabsorption in a molecule belonging to one of the 32 point groups. The geometrical factor in the final expression is identical to the one recently obtained by us for angle- and spin-resolved photoelectron spectroscopy of freely rotating, unpolarized polyatomics by using a modified definition of the angular momentum transferred from the ionizing radiation to the outgoing electron. The "reduced" amplitude in the present case contains, of course, both the Auger decay and photoionization matrix elements. The results derived herein, therefore, mean that identical geometrical analysis is applicable to spin-resolved Auger electron as well as photoelectron spectroscopies of molecules. We, in particular, show that the degree of spin-polarization of Auger electrons emitted following photoabsorption in C(infinity v) and D(infinity h) linear molecules can be completely characterized by four independent parameters. The procedure developed.herein is used to predict those molecular vacancies whose Auger decay will give rise to anisotropic angular distribution provided spin of the ejected electron is also observed. The degree of spin polarization of Auger electrons in this case is completely determined by a single parameter, say alpha(a), and does not depend upon the state of polarization of the absorbed photon. In the end, alpha(a) is predicted for some of the possible Auger transitions which may follow photoionization in 2a1 orbital of CCl4, SiCl4, and GeCl4. 2