Angle‐Resolved Photoelectron Spectroscopy of Randomly Oriented 3‐Hydroxytetrahydrofuran Enantiomers

Abstract

Circular dichroism in the angular distribution of valence photoelectrons emitted from randomly oriented 3-hydroxytetrahydrofuran enantiomers (ThS and ThR) has been observed in gas-phase experiments using circularly polarized vacuum ultraviolet (VUV) light. The measured dichroism for both ThS and ThR, acquired at the single magic angle theta=234.73 degrees and at photon energies of 22, 19, 16, and 14 eV, points to an asymmetric forward-backward scattering of the photoelectrons from their highest occupied molecular orbitals (HOMO) HOMO-1 and HOMO-2, of up to 5%, depending on the photon energy. The asymmetry reverses on exchange of either the helicity of the radiation or the configuration of Th. The photoionization dichroic D parameters of ThS and ThR have been measured and their values discussed in the light of LCAO B-spline density functional theory (DFT) predictions. While an acceptable agreement is found between the dichroic parameter measured and calculated at the highest photon energy for the HOMO and HOMO-2 orbitals of Th, a significant discrepancy is observed for the HOMO-1 state which is attributed to the floppiness of Th, in particular to the comparatively large sensitivity of the size and shape of its HOMO-1 on nuclear vibrational motion.

Emitter-site-selective photoelectron circular dichroism of trifluoromethyloxirane

“…Nowadays, PECD in the one-photon ionization of outer electrons is a well-established research area, which includes studies of molecular dimers [14], clusters [15], metal-organic complexes [16], and even small biological molecules [17][18][19][20]. Experimentally, this effect has been studied by tunable circularly polarized synchrotron radiation utilizing different methods of angle-resolved photoelectron spectroscopy.…”

Molecular and supramolecular chirality: R2PI spectroscopy as a tool for the gas‐phase recognition of chiral systems of biological interest

“…CDAD effects in randomly oriented (gas phase) chiral molecules were predicted by Ritchie 45 a few decades ago. Gas phase bromocamphor enantiomers were experimentally distinguished for the first time by Bowering et al 46 Shortly afterwards CDAD effects measured on rigid and floppy [47][48][49][50] chiral molecules demonstrate the usefulness of this methodology for highlighting the structural, conformational, and vibrational factors.…”

Experimental and theoretical cross sections for positron collisions with 3-hydroxy-tetrahydrofuran

“…Therefore, the AMP community has, to date, focussed its interest on those molecules that can be considered as proto-types, or analogues, for the "building blocks" of the nucleic acids. There is a general agreement among the members of this community [3][4][5][6] upon the reductionist philosophy whereby the physical, chemical, and biological properties of a system stem from the fundamental properties of its constituents and their a) Author to whom any correspondence should be addressed. Electronic mail: luca.chiari@flinders.edu.au.…”