Search for Asymmetric Interactions between Chiral Molecules and Spin-Polarized Electrons

We present our preliminary asymmetry results for the transmission of longitudinally spin-polarized electrons through a vapor of chirally-pure bromocamphor (C$_{10}$H$_{15}$BrO) molecules. We define the asymmetry for transmission as A $=$ [(I$\uparrow $-I$\downarrow )$/(I$\uparrow +$I$\downarrow )$]$_{R\, }$- [(I$\uparrow $-I$\downarrow )$/(I$\uparrow +$I$\downarrow )$]$_{L}$, where I$\uparrow $ (I$\downarrow )$ is the transmitted current measured for spin-up (spin-down) electrons and the ``L'' and ``R'' subscripts correspond to the left- and right-handed chirality of the molecules. At present, we have measured A at 1.5 eV electron scattering energy to be 5.4(2.5)*10$^{-5}$ when the transmitted, magnetically collimated electron beam is attenuated to 10{\%} of its initial value, corresponding to a pressure of a few millitorr in a cell of length 2.54 cm. This should be compared with the measurements of Mayer et al., where they report an asymmetry (by our definition) of about 3.4(0.2)*10$^{-4}$ for the same incident energy and electron beam attenuation [1]. We discuss possible reasons for this discrepancy. \\[4pt] [1] S. Mayer, C. Nolting, and J. Kessler, J. Phys. B 29, 3497 (1996).