AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Spark Discharge Generator (SDG) – A Promising Tool for Generation of Sub-nanometer Atomic Clusters
ANNE MAISSER, Konstantinos Barmpounis, Michel Attoui, George Biskos, Andreas Schmidt-Ott, TU Delft
Abstract Number: 615 Working Group: Nanoparticles and Materials Synthesis
Abstract Clusters consisting of less than 100 atoms can lead to materials with unique properties. Although investigations of atomic clusters date back to the 1970s, their use has been restricted mainly due to limitations in their production. The spark discharge generator (SDG), which has been widely employed to generate airborne nanoparticles of well-defined size and composition, can in principle be employed to produce clusters of a few atoms in high enough quantities. In the SDG varpor clouds are formed as a result of the high temperatures associated with the electrical breakdown between two electrodes. Upon expansion and cooling of these clouds the vapors nucleate to form clusters of a few atoms, which subsequently grow to larger particles by coalescence and agglomeration.
In this work we show that with high dilution flows in the spark region, the applicability of the SDG can indeed be extended to produce atomic clusters down to two atom ions. Similar results have been reported by Peineke et al. (2008) using a glowing-wire generator. The electrical mobilities of the generated clusters are measured by a high-resolution/high-transmission differential mobility analyser (DMA) using helium as a carrier gas. The electrical mobilities of the clusters measured in this work are in agreement with mobilities determined by conventional low-pressure drift-cell experiments (Weis et al., 2002). Our measurements also show that for small numbers of atoms (< 5), the mobility distribution patterns for Al, Ga, Pt and Ag are similar, showing odd-even oscillations due to electron pairing.
The results of this study point out that the SDG is a promising tool for generating atomic clusters suitable for many applications.
Peineke, C., Attoui, M., Robles, R., Reber, A.C., Khanna, S.N., Schmidt-Ott, A. (2009), J. Aerosol Sci., 40, 423-430.
Weis, P., Bierweiler, T., Gilb, S., Kappes, M.M. (2002), Phys. Rev. Lett., 355, 355-364.