In such an apparatus, infrared light makes the particles vibrate in different ways depending on their wave length, that is, the colour of the light. Many particles can be identified on the basis of the different vibrations they are able to generate. This is because the options for vibration are a factor of the molecule's shape. For example, a ring-shaped molecule pulses quite differently than a molecule with a long shape, even if it contains the same atoms. The vibration in question is revealed by the wavelength that registers on the scale of the infrared spectrometer.
Since the scientists in Berlin want to observe the structures of uncharged particles and can only produce very few of them, this procedure is excluded. Nevertheless, they use both methods, but combine them in a very ingenious way. Before they separate out the confusion of particles, they fire a very intense infrared laser with a certain wavelength at the mix. The laser light is so intense that it brutally separates the clusters. The intense light makes some of the particles vibrate so violently that they burst.
After selection with the infrared laser, the researchers send the mix of the particles that remain through a mass spectrometer. The particles that have been excited and destroyed by the infrared light of a certain wavelength leave hardly any traces in the mass spectrum. The scientists use a control experiment to establish that there is something missing from a certain point in the mass spectrum: they also separate a mix of gold clusters in the mass spectrometer, which they previously have not subjected to special treatment with the intensive infrared laser.
Conducting an experiment like this with a laser beam that has a single wave length is not very productive. Only a fu
|Contact: Dr. Andr Fielicke|