A Novel Mid-infrared Diode Laser Spectrometer With Supersonic Jet Expansion

Supersonic jet expansion is a very important technique in molecular spectroscopy, chemical reaction dynamics and new material preparation and fabrication. When supersonic jet expansion combines with laser spectroscopy, it can be used to simplify the molecular spectrum greatly and get more sharper spectral lines.The construction of a novel mid-infrared diode laser spectrometer combined with the supersonic jet expansion and an astigmatic multi-pass cell has been described in this dissertation. A LabView control program has been written for the spectrometer. The scan of the current of diode laser, the acquirement of absorption signals, the synchronous display and auto-save of the spectrum can be controlled simultaneously by this program. The main feature of this spectrometer is the introduction of an adjustable astigmatic multi-pass cell inside the supersonic jet vacuum chamber, which has a lot of advantages compared with other types of multi-pass cells, i.e., in increasing the absorption length and beam density.The Ar-N₂O Van der Waals complexes formed in the supersonic jet expansion with Ar and N₂O has been used to evaluate the performance of this spectrometer. The result shows that the spectrometer works well and has a very high resolution and sensitivity. This spectrometer can be used for further studies of high resolution spectrum of van der Waals complexes and clusters.