Asymmetry in elastic scattering of polarised electrons by optically active 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 , a camphor-like molecule containing an ytterbium atom, and also recently for bromocamphor. Asymmetries of about , 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 enantiomeric 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.

Section: Temporary Negative-ion Statesmentioning

confidence: 99%

Electron scattering from chiral molecules

Mayer

Nolting

Keßler

1996

“…Kessler (1982) suggested that multiple intramolecular Mott scattering can lead to phenomena analogous to optical activity. Hayashi (1985Hayashi ( ,1988 followed up this idea and calculated the spin polarisation for initially unpolarised electrons, scattered from some model molecules.…”

Section: Introductionmentioning

confidence: 99%

Spin-dependent electron scattering from oriented molecules

Blum

Thompson

1989

Elastic forward scattering of electrons from oriented (chiral and non-chiral) molecules is discussed. The main emphasis is on spin-dependent interactions. A general theory is derived in which the production of transverse and longitudinal spin polarisation is related to the structure of the target system and the geometry of the experiments. The different role played by spin-flip and non-flip processes is analysed. A dynamical theory is developed in which the collision is treated as a molecular event, and numerical results for the spin polarisations are presented for scattering from a chiral model molecule.

“…Theoretical estimates of such effects have been derived by Rich et al(1982). Hayashi (1985Hayashi ( , 1988 performed numerical calculations in the framework of multiple scattering theory and showed in particular that polarisation phenomena can be greatly enhanced if resonances are present.…”

Section: Introductionmentioning

confidence: 99%

Electron optical activity

Blum¹,

Fandreyer²,

Thompson³

1990

The passage of a beam of transversely polarised electrons through a sample of chiral (oriented and non-oriented) molecules is considered. The behaviour of the electronic spins, in particular the rotation of the initial polarisation vector, is discussed for various cases: (i) passage through an optically active refractive medium, (ii) forward scattering from oriented molecules and (iii) scattering from chiral randomly oriented molecules. Numerical results are presented for forward scattering from a chiral model molecule and the influence of the molecular orientation relative to the direction of the initial polarisation vector is discussed.