A novel interface for optimized coupling of gas chromatography and supersonic jet spectroscopy

The laser-based methods Laser Induced Fluorescence (LIF) and Resonance-Enha nced Multi-Photon Ionization (REMPI) can be used as highly selective detect ion modes for gas chromatography (GC). One major prerequisite for successfu l application of these defection methods is the availability of appropriate and reliable interfaces between the GC effluent and the molecular beam inl et. When a pulsed supersonic molecular beam (jet) source is used, the analy te molecules are efficiently cooled, allowing maximum selectivity of the la ser spectroscopic detection methods. However, several technical problems ha ve to be solved for practical realization of a GC-supersonic jet valve hyph enation. The pulsed jet interface should not interfere with the GC properti es and the supersonic molecular beam properties, Further a good working cyc le for the conversion from the continuously flowing GC current to the pulse d jet gas flow should he attained. This paper presents a novel setup of a G C-pulsed jet interface. The construction allows temporal and spatial compre ssion of the analyte molecules in jet gas pulse and thus an increase of the detection sensitivity. Moreover, the GC effluent comes into contact only w ith glass surfaces and not with valve parts like plungers and seals. This r educes memory effects and sample decomposition. The valve setup is tested w ith a REMPI-TOFMS instrument.