Spin-Dependent Effects in Electron-Molecule Scattering*

This talk will review the study of electron-molecule collisions that use electron polarization as a probe of the collision dynamics. Compared with atoms, early experiments with molecular targets seemed to indicate a ``quenching'' of spin-dependent effects. Measurements by the Rice [1] and Muenster [2] groups showed that exchange cross sections for electron-molecule scattering were much smaller than those for atoms. These discrepancies were never adequately explained. More recently, measurements by our group and at Muenster have given similar results when collision-induced fluorescence is observed. We will discuss these latter fluorescence measurements with H$_{2}$ and N$_{2}$ targets in detail, and show how rotational resolution of the electron-impact excited states can resolve, at least partially, the ``quenching'' puzzle. \\[4pt] [1] G.H. Rutherford et alii, Rev. Sci. Instrum. \textbf{61}, 1460 (1990). \\[0pt] [2] T. Hegemann \textit{et alii}, J.Phys.B \textbf{26}, 4607 (1993).