			15min:

HIGH-RESOLUTION IR ACTION SPECTRUM OF C₂H₂⁺.

SABRINA GÄRTNER, JÜRGEN KRIEG, OSKAR ASVANY AND STEPHAN SCHLEMMER, I. Physika\-lisches Institut, Universität zu Köln.

The method of Laser-Induced-Reactions (LIR), which is described in detail in Schlemmer et al. 2002, is used to obtain high-resolution infrared spectra of molecular ions.

Here, the endothermic reaction C₂H₂⁺~+~H₂~ rightarrow ~C₂H₃⁺~+~H is promoted by ro-vibrational excitation of the parent ion. A spectrum of the ₃ stretching vibration of C₂H₂⁺ is recorded by variation of the wavelength of a home-build OPO (Optical Parametric Oscillator) operating in the 3 micron region.

The experiments are carried out in a low temperature 22-pole ion trap where several hundred cold, mass selected parent ions are stored. Typical linewidths of the action spectra are 3~×~10^-3~cm^-1. First spectra for C₂H₂⁺ and their analysis will be presented. Other possible applications of LIR spectroscopy will be discussed.