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MO: Molekülphysik

MO 2: Experimentelle Techniken, Kalte Moleküle

MO 2.2: Talk

Monday, March 22, 2004, 11:45–12:00, HS 332

COOL MOLECULAR MICRO-BEAMS, FRIGID CLUSTERS, AND GELID MOLECULAR DIFFRACTION IMAGES — •Bretislav Friedrich — Fritz-Haber-Institut der MPG, Faradayweg 4-6, D-14195 Berlin

I will describe a versatile molecular beam source, employing supersonic flow, pulsing, and ablation in a way that minimizes size and pumping requirements. The performance of the source is exemplified by producing a cool pulsed supersonic molecular beam of CaF radicals, essentially without recourse to pumping. About 10¹² CaF molecules cooled to a terminal temperature of about 140 K are obtained per ablation pulse.

We have developed a general technique for orienting molecules, amenable to a wide variety of species and applications. The key aspect is to endow a polar molecule with a pseudo-first-order Stark effect. I will describe how this effect comes about and discuss its use in the detection of gas-phase HXeI clusters, generated by the photolysis of HI embedded in the outer shells of large Xen clusters.

I will also describe a versatile imaging detector for neutral atoms and molecules based on reactions with a vacuum-deposited silver surface. The detector is endowed with the Fellgett advantage, has a demonstrated sensitivity of several monolayers of molecules, and a dynamic range of at least 100:1. One of the immediate applications of the detector in our cold-molecule effort will be to determining the velocity distributions of slow/cold molecules. These are convoluted in a diffraction pattern and can be extracted with a high accuracy from an observed diffraction image.