AG Nano-Bio-Physics

Present research topics


 He droplets

Helium droplets containing between 103 and 1013 He atoms are formed via supersonic expansion of helium at stagnation pressures of 20 bar and temperatures between 6 K and 12 K into ultra-high vacuum. Evaporative cooling leads to a constant temperature of 0.37 K inside the He droplet, which represents an ideal environment for numerous investigations due to the fact that all vibrational and most of the rotational degrees of freedom are frozen out at these low temperatures. Electronically excited, positively or negatively charged helium atoms as well as electron bubbles are formed upon electron ionization. The interactions between these reactants and different dopants inside the helium droplets as well as on their surface are analyzed by means of high-resolution mass spectrometry.

Contact:
Univ. Prof. Dr. Paul Scheier
E-Mail: Paul.Scheier@uibk.ac.at
Phone: +43 (0)512 507 52660

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dianions

Recent Highlight:

Formation of Dianions in Helium Nanodroplets.
Andreas Mauracher, Matthias Daxner, Stefan E. Huber, Johannes Postler, Michael Renzler, Stephan Denifl, Paul Scheier and Andrew M. Ellis,
Angewandte Chemie Int. Ed. Volume 53, Issue 50, 2014, Pages: 13794–13797,

DOI: 10.1002/anie.201408172



 STM

Different kinds of nanoparticles, produced inside of helium nanodroplets or by magnetron sputtering, are deposited on graphite or other single crystalline metal surfaces and analyzed by means of scanning tunneling microscopy. The device used in our institute is operated under ultra-high vacuum conditions (10-14 bar) and pictures can be recorded at temperatures between 20 K and 1500 K. Besides size and shape of the particles it is also possible to gain information about their electronic properties, such as density of states or electric conductivity.

Contact:
Univ. Prof. Dr. Paul Scheier
E-Mail: Paul.Scheier@uibk.ac.at
Phone: +43 (0)512 507 52660

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silicon

Recent Highlight:

Evaporation of silicon nanoparticles under scanning tunneling microscope control.
Michaela Hager, Alexander S. Berezin, Tamara T. Zinkicheva, Diethard K. Bohme, Michael Probst, Paul Scheier and Renat R. Nazmutdinov,
Chemical Physics Volume 425, 2013, Pages: 141-147

DOI: 10.1016/j.chemphys.2013.08.012



 Ion-surface collisions

Ion-surface reactions have a broad area of applications ranging from astrochemistry and cluster physics to fusion research, where these kind of reactions appear in so-called plasma-wall interactions. Moreover, surface-induced ionization processes are a relatively new research topic, in contrast to ionization processes in gas phase, which makes it an even more interesting field. Especially the complexity of the reactions at the surfaces makes theoretical considerations extremely difficult and hence increases the importance of experimental data on this topic even more..

The so-called BESTOF device, a tandem mass spectrometer, allows for observation of such ionization processes at the surface sample and furthermore provides interesting data on sputtering processes and interactions of different projectiles with the surface material or material deposited on the surface. After passing the sector field mass spectrometer the mass-selected projectile ions hit the surface at a distinct incident energy (between 15 eV and 100 eV). The product ions resulting from these reactions can be identified and quantified with the subsequent time-of-flight mass spectrometer.

Contact:
Univ. Prof. Dr. Paul Scheier
E-Mail: Paul.Scheier@uibk.ac.at
Phone: +43 (0)512 507 52660

hcn_cover

Recent Highlight:

Formation of HCN+ in Heterogeneous Reactions of N2+ and N+ with Surface Hydrocarbons.
Martina Harnisch, Alan Keim, Paul Scheier, Zdenek Herman,
The Journal of Physical Chemistry A, Volume 117, Number 39, 2013, Pages: 9653-9660,

DOI: 10.1021/jp312307a