iMOS Master: Infrared Spectroscopy of Highly Reactive Aggregates in…

Infrared Spectroscopy of Highly Reactive Aggregates in Helium Nanodroplets

Daniel Leicht

In my master thesis I investigated the infrared (i.e. the vibrational) spectrum of helium solvated allyl radicals. The radicals were produced by pyrolysis of 1,5-hexadiene and trapped in superfluid helium nanodroplets. The helium droplet beam was overlapped by the output of a tunable infrared laser to obtain the infrared spectrum. After obtaining the experimental infrared spectrum ab initio calculations were carried out as a basis of the spectral assignment. Different DFT methods were compared with respect to their viability since open-shell species often pose a problem in such computations.


Spin density surface of the allyl radical.

Based on the quantum chemical calculations five CH-stretching bands were assigned to the observed spectral features. The rotational fine-structure of the recorded spectrum was investigated as well. Due to the very low droplet temperature of 0.37 K, also weakly bound complexes can be studied using this technique. As an outlook I proposed an investigation of the allyl:HCl complex, which has been carried out and published at a later time.

After finishing his iMOS Master’s thesis Daniel Leicht started his PhD research in the group of Prof. Havenith.

Link to  Master course in Molecular Sciences and Simulation (iMOS) at Ruhr-University Bochum