Electron scattering rom chiral molecules

Detailed information is given on an experiment which was carried out to investigate the spin-dependent attenuation of electron beams transmitted through a vapour of chiral molecules. The experiment is considered to be the first verification of electron dichroism. A transmission asymmetry for longitudinally polarized electron beams of opposite helicity was observed for Yb(hfc)3, a camphor-like molecule containing an ytterbium atom, and also recently for bromocamphor. Asymmetries of about 1.5 x 10-4, which is clearly above the detection limit, were measured for both targets at electron energies between 0.5 and 10 eV. No asymmetry was found when enantiometric camphor vapour was used as the target, thus contradicting a result which has been previously published by another group. The asymmetry measurements are compared with electron transmission spectra, which show that the energies where resonant temporary-ion formation takes place and those of the extrema of the asymmetry agree to a great extent. (author)