High-resolution FTIR and Diode Laser Spectroscopy of Supersonic Jets
| Autor: | Martin Quack, Veronika Horká-Zelenková, Marcel Snels, Hans Hollenstein |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
010304 chemical physics
Chemistry Infrared spectroscopy 010402 general chemistry Laser 01 natural sciences 7. Clean energy 0104 chemical sciences Cavity ring-down spectroscopy law.invention symbols.namesake law 0103 physical sciences symbols Molecule van der Waals force Fourier transform infrared spectroscopy Atomic physics Molecular beam Tunable laser |
| Zdroj: | info:cnr-pdr/source/autori:Marcel Snels, Veronika Horka-Zelenkova, Hans Hollenstein and Martin Quack./titolo:High-resolution FTIR and Diode Laser Spectroscopy of Supersonic Jets/titolo_volume:/curatori_volume:/editore:/anno:2010 Handbook of High-resolution Spectroscopy info:cnr-pdr/source/autori:M.Snels, V. Horka-Zelenkova, H.Hollenstein and M.Quack/titolo:High-resolution FTIR and Diode Laser Spectroscopy of Supersonic Jets/titolo_volume:/curatori_volume:/editore:/anno:2011 |
| Popis: | Fourier transform infrared (FTIR) spectrometers and tunable diode lasers in combination with a supersonic molecular beam expansion are a perfect tool for the investigation of molecules, ions, and radicals at low temperatures. The internal degrees of freedom of the molecules are adiabatically cooled to very low temperatures and thus only low-lying energy levels are populated. The reduction of the number of populated levels at low temperatures makes the assignment of the spectra much easier as compared to the congested room-temperature spectra. Under certain conditions, the Doppler linewidths are greatly reduced, corresponding to very low effective translational temperatures. Supersonic expansion also provides a suitable method for producing and investigating van der Waals clusters and hydrogen-bonded complexes. Unstable species such as radicals and ions can be efficiently produced and studied in a molecular beam. The low rotational temperature allows for the study of nuclear spin symmetry conservation or conversion between nuclear spin isomers. A molecular beam expansion can be obtained by expanding gas through a slit or a circular nozzle. Both expansion geometries can be used in combination with a multipass optical setup and with cavity ring down spectroscopy, which enhances the effective absorption path length. Cooling of the molecules can be promoted by seeding in noble gases. This article summarizes the general aspects of the experimental technique as well as current developments. To demonstrate how powerful the combination of a molecular beam expansion with tunable diode laser and FTIR spectroscopy can be, we report results on some important current examples. Keywords: FTIR; supersonic jet; diode laser; molecular beam; clusters; van der Waals complexes; hydrogen bonds; nuclear spin symmetry conservation; infrared spectroscopy; isotopes |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|