Hannover 2013 – scientific programme
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MO: Fachverband Molekülphysik
MO 8: Spectroscopy in He-Droplets
MO 8.3: Talk
Monday, March 18, 2013, 17:00–17:15, F 107
Studying Molecular Aggregation below 1 K — •Pablo Nieto, Torsten Endres, Daniel Habig, Gerhard Schwaab, and Martina Havenith — Department of Physical Chemistry II, Ruhr-Universität Bochum, Germany
Spectroscopy of doped molecules in superfluid helium droplets is a very promising and fast developing area for the study of molecular aggregation at temperatures below 1 K. These experiments can be seen as a part of the effort to understand molecular interactions at the microscopic level and low temperatures. In this presentation some examples carried out in our lab in Bochum will be explained to illustrate the great potential of this technique for the study of molecular aggregates in a controlled environment.
As a first example, pyridine dimers were investigated in the C-H asymmetric vibration region (2980-3100 cm−1) by means of infrared depletion spectroscopy. The cluster sizes related to each resolved band were determined by means of pick-up pressure intensity dependence as well as with mass sensitive depletion spectra. Furthermore, the study of the different bands on applying a DC electric field provided a very valuable tool for obtaining conformational information. The assignment of the pyridine dimers structures present in helium droplets was carried out by combining the experimental results with ab initio calculations. Results for other systems such as the pyridine-water heterodimer will also be discussed.