Abstract
We present an experimental X-ray photoelectron circular dichroism (PECD) study of liquid fenchone at the C 1s edge. A novel setup to enable PECD measurements on a liquid microjet [Malerz et al., Rev. Sci. Instrum., 2022, 93, 015101] was used. For the C 1s line assigned to fenchone's carbonyl carbon, a non-vanishing asymmetry is found in the intensity of photoelectron spectra acquired under a fixed angle in the backward-scattering plane. This experiment paves the way towards an innovative probe of the chirality of organic/biological molecules in aqueous solution.
Highlights
Recognition, requires interaction with another chiral entity
A common example is the interaction with circularly polarized light (CPL), which gives rise to the well-known circular dichroism (CD) effect in absorption. 3,4 Relatedly, chiral electrons have been shown to discriminate for the molecularlevel handedness of a sample. 5,6
It is of great appeal that elements of these two techniques are combined in yet another effect that discriminates between different enantiomers of a species, namely photoelectron circular dichroism (PECD)
Summary
Recognition, requires interaction with another chiral entity. A common example is the interaction with circularly polarized light (CPL), which gives rise to the well-known circular dichroism (CD) effect in absorption. 3,4 Relatedly, chiral (spin-polarized) electrons have been shown to discriminate for the molecularlevel handedness of a sample. 5,6. It is of great appeal that elements of these two techniques are combined in yet another effect that discriminates between different enantiomers of a species, namely photoelectron circular dichroism (PECD) This term designates an asymmetry in the angle-resolved photoelectron (PE) flux after ionization of a sample of chiral molecules with circularly polarized light. The effect requires a suitable geometry of the experiment, as it vanishes in the plane perpendicular to the photon propagation direction (‘dipole plane’) It can be observed as a difference of photoelectron intensity between two measurements, in which either (1) the same sample is probed by left- vs right-handed circularly polarized light, or (2) the same sample is probed by any helicity of the light, and electrons are collected under two different angles, one in the forward and the other in the backward scattering direction, with the two angles being mirror imaged at the dipole plane, or (3) by probing the two different enantiomers of a substance with either helicity, at an angle outside of the dipole plane. A small subset of the data from this project was already used for illustrative purposes in an apparatus paper that some of the authors have recently published. 33
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