Siegel der Universität

Universität zu Köln
Mathematisch-Naturwissenschaftliche Fakultät
Fachgruppe Physik

I. Physikalisches Institut

Cluster Sources

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Scheme of the laser ablation

The type of source employed in our spectrometer is a laser ablation source. To produce the carbon clusters, high-energy UV laser pulses are focused onto a rotating graphite rod. Thereby, carbon fragments are ablated and carried out by pulses of Helium gas at a backing pressure of 10-20 bars. Small carbon clusters form in the dense plasma within the slit source, before adiabatically expanding into the vacuum chamber. The background pressure in the vacuum chamber is kept below 0.1 mbar. With every single laser pulse a total amount of roughly 1013 - 1014 clusters of different sizes is produced.

Either an excimer laser (248 nm) or a Nd:Yag laser (266 nm) are used for generation of the high-energy laser pulses.

Tests of different sources basing on the discharge of Acetylene gas are still in progress.

Below you can find some pictures of different views of the jet. Click on a picture to get a closer look.


Topview of the supersonic jet Sideview of the supersonic jet IR path through the jet
Topview of the supersonic jet Sideview of the supersonic jet Optical path of the IR-laser through the jet