Electron Dichroism: Interaction of Spin-polarised Electrons with Chiral Molecules

Keßler, J.

doi:10.1071/p97082

Cited by 2 publications

(2 citation statements)

References 2 publications

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“…(4) As was predicted theoretically by Farago [22], and by Fandreyer et al [23], the spin-orbit (SO) interaction plays an important role in the formation of the electron dichroism (ED) in the electron scattering from chiral molecules. In corresponding experiments for the scattering of spin-polarized electrons from chiral molecules in the gas phase by Mayer and Kessler [24], Nolting et al [25], and Kessler [26], the scattering cross sections showed a spin-related dependence. While no detectable effect was found in the case of camphor consisting only of light elements, for bromocamphor and other chiral molecules containing at least a heavier atom small asymmetries of the order of 10 −4 were observed.…”

Section: Target Selection and Molecular Structurementioning

confidence: 99%

“…An additional advantage for such a comparison is the rigid bridged structure of both molecules, which eliminates any uncertainty originating from the occurrences of multiple conformations. Furthermore, in analogy to the ED experiments, a possible spin-dependent effect should be considerably stronger in bromocamphor than in camphor due to the Br atom with Z =35 [24][25][26].…”

Section: Target Selection and Molecular Structurementioning

confidence: 99%

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Circular dichroism in valence photoelectron spectroscopy of free unoriented chiral molecules: Camphor and bromocamphor

et al. 2004

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The circular dichroism in the photoelectron angular distribution was investigated for valence photoionization of randomly oriented pure enantiomers of camphor and bromocamphor molecules using circularly polarized light in the vacuum ultraviolet. The forward-backward electron emission spectra were recorded simultaneously with two spectrometers at several opposite angles relative to the propagation direction of the photon beam and compared for each of the two substances. Measurements were also carried out for reversed light helicity and opposite molecular handedness. For the left-and right-handed enantiomers of both molecules we observed asymmetries of comparable magnitude up to several percent. The measured asymmetry parameters vary strongly for different orbital binding energies and also for the selected photon energies in the valence region. The results for both molecules are compared. They suggest a strong influence of the final states on the asymmetry, depending on the chiral geometry of the molecular electronic structure, as well as a significant dependence on the initial states involved. They also confirm theoretical predictions describing the effect in pure electric-dipole approximation.

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Section: Target Selection and Molecular Structurementioning

confidence: 99%

Section: Target Selection and Molecular Structurementioning

confidence: 99%

Circular dichroism in valence photoelectron spectroscopy of free unoriented chiral molecules: Camphor and bromocamphor

et al. 2004

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Magnetically Aligned Grains as a Ubiquitous Source of Spin-polarized Electrons and Chiral-symmetry-breaking Agents

Hoang

2024

ApJ

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The unique biosignature of life on Earth is the homochirality of organic compounds, such as amino acids, proteins, and sugars. High-energy spin-polarized (spinup or spindown) electrons (SPEs) from the β decay of radioactive nuclei have been proposed as a source of symmetry breaking, leading to homochirality; however, their exact role is much debated. Here, we propose magnetically aligned dust grains as a new source of SPEs, due to the photoemission of electrons having aligned spins by the Barnett effect. For the interstellar UV radiation field of strength G UV, we find that the SPE emission rate is Γ pe SPE ∼ 10 − 14 G UV electrons per second per H, the fraction of spin-polarized to total photoelectrons is ∼10%, and the SPE yield (photoelectron number per UV photon) can reach ∼1%, using the modern theory of grain alignment. SPEs emitted from aligned grains could play an important role in chiral-induced spin-selectivity-driven reduction chemistry in the icy grain mantles, producing an enantiomer excess of chiral molecules formed on the grain mantle. Finally, we suggest magnetically aligned grains could directly impact the enantio-selectivity through the chiral-induced spin-selective adsorption effect and exchange interaction. We estimate the disalignment of electron spins and depolarization by elastic scattering using the Mott theory and find that these effects are negligible for low-energy SPEs, so that the spins of SPEs remain well aligned during their journey through dust grains and the gas. Our proposed mechanism might explain the chiral asymmetry of prebiotic molecules detected in numerous comets, asteroids, and meteorites.

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Electron Dichroism: Interaction of Spin-polarised Electrons with Chiral Molecules

Cited by 2 publications

References 2 publications

Circular dichroism in valence photoelectron spectroscopy of free unoriented chiral molecules: Camphor and bromocamphor

Circular dichroism in valence photoelectron spectroscopy of free unoriented chiral molecules: Camphor and bromocamphor

Magnetically Aligned Grains as a Ubiquitous Source of Spin-polarized Electrons and Chiral-symmetry-breaking Agents

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