An Attempt to Observe Mott Scattering Optically in Krypton.

We present recent measurements of the relative Stokes parameters for the 811 nm Kr (4p$^{5}$5p)[5/2] $^{3}$D$_{3}\to $(4p$^{5}$5s)[3/2] $^{3}$P$_{2}$ transition excited by polarized electron impact. Of particular interest is the spin-normalized linear polarization fraction P$_{2}$/P$_{e}$. Because the upper excited state is well \textit{LS}-coupled, a near-threshold observable non-zero value of P$_{2}$ implies spin-orbit coupling between the target and continuum electron (an optical analog of Mott scattering) [1]. This work is a continuation of a previous paper wherein a cascade free measured P$_{2}$/P$_{e}$ of 0.028(26) is compared to a theoretical 31-state Breit-Pauli R-matrix calculation which predicts a value of 0.032 [2]. Thus our earlier data is consistent with both the theory and zero. Our current effort is to increase the precision of these measurements. \newline \newline [1] N. Anderson and K. Bartschat, \textit{Polarization, Alignment, and Orientation in Atomic Collisions}, (Springer-Verlag, New York, 2001). \newline [2] B.G. Birdsey \textit{et al}., Phys. Rev. A \textbf{60}, 1046 (1999).