Isaak Unger

post doctoral at Department of Physics and Astronomy, Molecular and Condensed Matter Physics

Email:
Isaak.Unger[AT-sign]physics.uu.se
Visiting address:
Ångströmlaboratoriet, Lägerhyddsvägen 1

Postal address:
Box 516
751 20 UPPSALA

Also available at

My courses

Biography

I come from Berlin, Germany where I studied physics at Humboldt University and finished both, my bachelor and my master in the group 'electronic properties and superconductivity'. During studies at Humboldt University my interest was in solid state physics - especially in two topics: Transparent conducing oxides and layered crystals. The former are interesting as 'window materials' for solar cells and layered crystals are model systems to study phase transitions (e.g. charge density waves) in solids. During my time as a master student, I also worked as a scientific assistant in the group 'electronic properties and superconductivity'. I was responsible for the scanning tunnelling microscope (STM) of the group and carried out all measurements with this machine, which incorporated the 'classic' scanning tunnelling microscopy as well as scanning tunnelling spectroscopy. As a master student I broadened my activity and became familiar with the growth of crystals (chemical vapor transport) and angle resolved photoelectron spectroscopy (ARPES).

After I finished my master, I became a PhD student in Bernd Winter's group at Helmholtz Zentrum Berlin für Materialien und Energie. Here, the focus of the research shifted from solids to liquids, mostly aqueous solutions, and the tool of our choice to investigate them was photoelectron spectroscopy (PES / XPS). My research centred on charge transfer processes between molecules in solution on the femtosecond timescale. I applied Auger electron spectroscopy after core-ionisation to disentangle entwined autoionization processes. These processes happen either in the initial molecular geometry or they are mediated by a proton transfer along a hydrogen bond. All these processes give rise to reactive cationic species, which might play an important role in radiation induced damage to living tissue (e.g. consider intercontinental flights, medical radiation therapy or astronauts). Some of these processes are sensitive to the hydrogen-bond strength between molecules and can yield molecular-level information about hydrogen bonds, which govern over many physical properties of aqueous solutions.

After my time as a PhD student, I decided that it is high time to go abroad and so I became a member of Olle Björneholm's group in Uppsala. Here, we still use photoelectrons spectroscopy, but the focus of the scientific questions have shifted toward environmental science and studies of clusters and aerosols complement our research on liquids.

Research

My research focusses on photoelectron spectroscopy / Auger electron spectroscopy of liquids and to smaller extend also on aerosols and clusters. The central issues I address in my research are charge transfer processes between molecules in solution, surface enrichment / depletion of solutes and the properties of the hydrogen-bond network in water and aqueous solutions.

Publications

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