A joint research project of the ‘Ultrafast Coherent Dynamics‘ group, headed by Prof. Matthias Wollenhaupt, and the group of Prof. Thomas Baumert at the University of Kassel, was presented on the cover page of the renowned european science journal „CHEMPHYSCHEM“. Subject of the article is the investigation of Photoelectron Circular Dichroism (PECD) of chiral molecules photoionized by circularly polarized femtosecond laser pulses.

Chiral molecules exist in two species (enantiomers) being mirror images of one another which cannot be overlapped by rotations – just like, for example, our human hands. In biology and medicine this apparently tiny effect has far-reaching consequences. For instance, the two enantiomers of a chiral molecule can have a completely different smell and taste, respectively. In many cases chiral pharmaceutics have fundamentally different effects. Therefore, sensitive methods for effective chiral recognition is essential for many fields of application.

The PECD describes differences in the photoelectron emission in forward/backward direction with respect to the laser beam. The effect is orders of magnitude stronger than conventional circular dichroism. The analysis of physical mechanisms presented in this contribution highlights the role of intermediate resonances for the PECD. In addition, quantitative measures are derived for the multiphoton PECD to develop this technique into a versatile tool for research and analytics of chiral molecular systems. Applications range from the determination of enantiomeric excess on highly dilute gas-phase samples to additional routes to determine the absolute configuration of chiral molecules.

Read the article in "CHEMPHYSCHEM" here.

[13.02.2015]