讲座题目：Infrared and Microwave Spectroscopy of Molecules Embedded in Helium Nanodroplets
Helium nanodroplet spectroscopy is a versatile method to study spectra of a wide range of molecular species at ultra-low temperatures. Helium nanodroplets can consist of about a thousand to millions of helium atoms and attain a temperature of 0.4 K through evaporative cooling. This temperature is below the lambda point of 4He and the droplets are therefore superfluid. These properties make helium nanodroplets an ideal substrate to cool and to stabilize molecules and molecular clusters for spectroscopic studies.
In this presentation, I will give an overview over the experimental aspects, including some details of the instrument setup and the operating principle. Helium nanodroplet spectra of ammonia, methanol, and hydrogen peroxide will be presented and interpreted. A progress report on our current efforts to couple the helium nanodroplet instrument to a linear ion trap will be given.
In the second part of the talk, some recent results of our studies on the stepwise solvation of asymmetric top molecules with helium atoms will be presented. Indicators of microscopic superfluidity emerge at cluster sizes of less than 20 helium atoms.
Wolfgang Jäger received his PhD degree in Chemistry from the Christian Albrechts University in Kiel, Germany, in 1989. He joined the Department of Chemistry at the University of Alberta, Edmonton, Canada, in 1995 after spending time as postdoctoral fellow and research associate at the University of British Columbia, Vancouver, Canada. He was promoted to Associate Professor in 2001 and to the rank of Full Professor in 2003.
Professor Jäger’s research is multifaceted and includes fundamental studies of intermolecular interactions using spectroscopic investigations of weakly bound complexes and clusters, development of atmospheric trace gas sensing techniques that utilize solid state infrared diode lasers, photoreaction chamber studies of aerosol formation, and design and fabrication of external cavity lasers using MEMS technology. His work has resulted in more than 180 publications thus far.
For his scientific achievements, Professor Jäger was awarded the NSERC Steacie Memorial Fellowship in 2002, in 2004 he became a Tier I Canada Research Chair in Cluster Science which was renewed in 2011, and in 2008 he was elected Fellow of the Royal Society of Canada. From 2009 to 2010, he spent a sabbatical year at the Fritz Haber Institute of the Max Planck Society in Berlin, Germany, which was funded by a prestigious Humboldt Fellowship.