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Universität zu Köln
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Mathematisch-Naturwissenschaftliche Fakultät
Fachgruppe Physik

I. Physikalisches Institut

Methods

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Jet Spectroscopy

Description

Carbonaceous clusters are produced through laser ablation. High-energy UV laser pulses (355 nm) are focused onto a rotating rod composed of appropriate precursor material (graphite, SiC, etc.). Products are carried through a 1cm reaction channel by pulses of Helium gas kept at a backing pressure of 10-20 bar and expand adiabatically 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.

Molecules are investigated at high spectral resolution using infrared radiation provided by quantum cascade lasers or optical parametric oscillators. ...more

Figure(s)

Edge-on (left) and face on views of a supersonic jet from a slit-nozzle.

Instruments

Carbon Cluster Experiment
In the carbon cluster experiment, part of the infrared probe radiation is guided through a reference gas cell and a reference interferometer for calibration purposes. The major fraction is guided into a vacuum chamber and through a Herriott-type multireflection cell where it is intersecting the free jet harboring the clusters perpendicularly close to the exit of a slit nozzle. After having passed the chamber, the infrared beam is detected using sensitive InSb or HgCdTe detectors and its signal is digitized using an USB oscilloscope.
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Publications