Dresden 2011 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 10: Cluster

MO 10.7: Vortrag

Dienstag, 15. März 2011, 12:00–12:15, MER 02

Comprehensive study of supersonic beams of CO₂ close to the critical point — •Wolfgang Christen, Bo-Gaun Chen, Stefan Heinig, and Klaus Rademann — Humboldt-Universität zu Berlin, Institut für Chemie, Brook-Taylor-Str. 2, 12489 Berlin

The formation and growth of clusters in the gas phase is of fundamental relevance in a number of research fields as for instance atmospheric and environmental chemistry, chemical engineering, and process technology. In spite of a great deal of theoretical and experimental work open questions remain, including, for example, phase transitions close to the critical point.
Extending our earlier work¹ on pulsed, supersonic beams of pure CO₂ we present a systematic investigation of the mean flow velocity as a function of the stagnation conditions. The thermodynamic parameters comprise a wide range from medium to high pressures and sub- to supercritical temperatures with high accuracy². Velocity distributions are determined using high resolution and mass-resolved time-of-flight measurements. The experimental results are compared with recent model predictions^3,4. In particular we discuss the influence of the spinodal and the issue of liquid vs. solid clusters.

¹W. Christen, K. Rademann, U. Even, J. Chem. Phys. 125, 174307, 2006. ²W. Christen, T. Krause, K. Rademann, Rev. Sci. Instrum. 78, 073106, 2007. ³W. Christen, K. Rademann, Phys. Scr. 80, 048127, 2009. ⁴W. Christen, K. Rademann, U. Even, J. Phys. Chem. A 114, 11189, 2010.