Düsseldorf 2007 – wissenschaftliches Programm

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SYMC: Symposium Molecular Collisions at ultracold temperatures

SYMC 1: Molecular collisions at ultracold temperatures I

SYMC 1.1: Hauptvortrag

Montag, 19. März 2007, 14:00–14:30, 5D

Towards the study of ultracold ion-molecule reactions — •Timothy Softley, Martin Bell, David Carty, Alexander Gingell, and James Oldham — Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Rd, Oxford, OX1 3TA, United Kingdom

In the sub-Kelvin temperature range, the de Broglie wavelength of colliding species becomes long compared to molecular dimensions and a range of quantum effects will play an important role in determining the dynamics of reactive collisions. However, only reactions with a low activation barrier will have rates that are amenable to study. Ion-molecule reactions are a general category of reactions with negligible activation barriers; free-radical insertion reactions are another suitable category, as are reactions of electronically excited species. In this presentation we describe the development of experiments which are geared towards studying ultracold ion-molecule chemistry. A Coulomb-crystal device has been set up in which calcium ions are laser cooled into the milliKelvin range. The characterization of the temperature of the ions formed in regular arrays, and the possibilities for sympathetic cooling of state-selected molecular ions will be discussed. This device is to be combined with a low-temperature source of neutral dipolar species, which are produced by either a quadrupole guide velocity selector, or by a 130-stage Stark decelerator. We are also developing a decelerator for Rydberg molecules, and a source of ultracold atoms based on photodissociation. Progress towards combining these sources for reactive studies will be discussed.