Berlin 2014 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 4: Electron Dynamics in Chiral Systems SYCS 1 (with MO)

A 4.2: Hauptvortrag

Montag, 17. März 2014, 11:00–11:30, Audimax

Electron Scattering in Chiral Photoionization: probing fundamental electron-molecule interactions to chiral molecular recognition — •Ivan Powis — University of Nottingham, Nottingham, UK

The photoionization of chiral species by circularly polarized light produces an asymmetric angular distribution of photoelectrons. The forward-backward asymmetries are typically 3-30%, perhaps three orders of magnitude greater than in other chiroptical phenomena. A peculiarity of this phenomenon is a much enhanced sensitivity to scattering phase shifts, and photoelectron Circular Dichroism (PECD) experiments measuring these asymmetries offer fresh generic insights into electronnuclear interactions.

The magnitude of the PECD effect offers a unique sensitivity to probe, in dilute environments, static and dynamic aspects of molecular chirality per se. Absolute molecular configuration (handedness)- relevant for pharmaceutical, odour, and pesticide production - can be reliably determined by eliminating the common liquid phase interference from induced chiral structure in a solvation shell. More subtle features of molecular conformation (shape) are similarly exposed in this manner. The concept of "shape" is important in many approaches to molecular recognition in e.g. understanding enzyme interaction at receptor sites. Weak, non-bonding molecular interactions drive this recognition. We will conclude by showing how the structure of a prototype self-assembling complex, built by H-bond chiral-recognition between smaller chiral molecules, can be probed in cold molecular beam environments by PECD.