Conformational Effects on Circular Dichroism in the Photoelectron Angular Distribution

Abstract

The B-spline density-functional method has been applied to the conformers of the (1R, 2R)-1,2-dibromo-1,2-dichloro-1,2-difluoroethane molecule. The cross section, asymmetry, and dichroic parameters relative to core and valence orbitals, which do not change their nature along the conformational curve, have been systematically studied. While the cross section and the asymmetry parameter are weakly affected, the dichroic parameter appears to be rather sensitive to the particular conformer of the molecule, suggesting that this dynamical property could be a useful tool for conformational analysis. The computational method has also been applied to methyl rotation in methyloxirane. Unexpected and dramatic sensitivity of the dichroic-parameter profile to the methyl rotation, both in the core and valence states, has been found. Boltzmann averaging over the conformers reproduces quite closely the profiles previously obtained for the minimum-energy conformation, which is in good agreement with the experimental results.

Photoelectron circular dichroism: Chiral asymmetry in the angular distribution of electrons emitted by (+)‐S‐carvone

“…In other words the chiral part of the angular distribution is much more sensitive to molecular conformation than the regular b parameter. This is now expected behavior from other studies 11,13,20 and arises because of the different way in which the chiral b fAE1g 1 coefficient is sensitive to phase shifts induced as the electron scatters from the ion core, even when the relative phase differences are quite small. 12 We can anticipate that the dominant contribution to the experimental PECD comes from the equatorial conformers, based upon the much larger predicted populations of this group (Table 1).…”

“…7,[11][12][13] At the same time the successful application of theoretical models to treat the experimental data provides clear evidence that not just molecular conformation, but also absolute configuration could be assigned with such experimental data.…”

Vibrationally induced inversion of photoelectron forward-backward asymmetry in chiral molecule photoionization by circularly polarized light

“…Stener and co-workers first demonstrated through numerical calculations a very dramatic dependence of the predicted chiral b 1 parameter on molecular geometry26. In fact, the example they chose to consider was a rotation of the methyl group in methyl oxirane approximating to the torsional motion in the molecule.…”

Conformational Effects in Photoelectron Circular Dichroism of Alaninol

“…Previous work revealed the dynamical properties of the CD in photoelectron spectroscopy as a useful tool for conformer analysis: the conformer influence on the core ionization of carvone [12,13] and on the valence ionization of glycidol, [14] and a detailed theoretical analysis showing the influence of geometry on the dichroism parameter. [15] Herein, we present data for a linear, saturated, bifunctional molecule amenable to intramolecular interactions and different conformations. This extension is particularly important from an experimental and theoretical point of view because it puts under scrutiny the technique and the computational model for the analysis of a large set of molecular valence states.…”