Dresden 2017 – scientific programme

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O: Fachverband Oberflächenphysik

O 41: Nanostructures at Surfaces: Metals, Oxides and Semiconductors II

O 41.4: Talk

Tuesday, March 21, 2017, 14:45–15:00, REC/PHY C213

Aggregation behaviour of silver clusters in room temperature ionic liquids — •Stefanie Roese, Alexander Kononov, Florian Lippert, and Heinz Hövel — Fakultät Physik / DELTA, TU Dortmund, Otto-Hahn-Str. 4, 44221 Dortmund, Germany

Room temperature ionic liquids (RTIL) are well-known stabilizers for nanoparticles [1]. For now only a few studies of the stability of nanoparticles in RTILs are available [2], nevertheless the nanoparticle stability is of critical importance in controlling aggregation processes.

2 nm silver nanoparticles with a well-characterized size distribution (± 0.6 nm) are preformed in a supersonic nozzle expansion [3] and deposited afterwards into the ionic liquid. The cluster plasmon is investigated in-situ by UV/Vis absorption spectroscopy during cluster deposition as well as in temperature dependent measurements after deposition [4]. We observed that the storage temperature as well as the choice of anion and cation influences the cluster stability on timescales of several days. An activation energy for different aggregation states was calculated.

The geometric cluster structure is determined in first EXAFS measurements performed at beamline P64, DESY, where the effect of aggregation can be seen in a change in the resulting lattice constant.

[1] J. Dupont, J. D. Scholten, Chem. Soc. Rev. 39, 1780 (2010). [2] K. Richter, A. Birkner and A. Mudring, Phys. Chem. Chem. Phys. 13, 7136 (2011). [3] H. Hövel, S. Fritz, A. Hilger, U. Kreibig and M. Vollmer, Phys. Rev. B 48, 18178 (1993). [4] D. Engemann, S. Roese and H. Hövel, J. Phys. Chem. C, 120, 6239 (2016).