Konstanz 1998 – scientific programme

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MO: Molekülphysik

MO 11: Spektroskopie II

MO 11.3: Talk

Thursday, March 19, 1998, 11:30–11:45, M629

Direct absorption spectroscopy in slit nozzle plasmas — •Harold Linnartz, Thomas Speck, and John P. Maier — Institute for Physical Chemistry, Klingelbergstrasse 80, CH4056 Basel

Slit jet expansions are routinely used for direct absorption spectroscopy of weakly bound molecular complexes, consisting from neutral species. In the last years attempts have been undertaken via plasma formation to extend this method to ionic complexes. Here a new technique is presented, based upon the combination of tunable diode laser spectroscopy and electron impact ionization in a supersonic slit jet expansion.
On the example of rotationally resolved spectra of N₄⁺ the characteristics of this intense source for cold molecular ions will be discussed [1]. Furthermore, the first direct measurement of an ionic complex (Ar-HN₂⁺ and Ar-HCO⁺) will be presented [2]. A good understanding of these species yields information of chemical reactions at the fundamental level of molecular motions. As most infrared and submillimeter studies are based on direct absorption, this new approach will be generally applicable.

[1] T. Ruchti et al, J. Chem. Phys. 105 (1996) 2591

[2] T. Speck et al, J. Chem. Phys. 107 (1997) 8706