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QUCC Report Summary

Project ID: 617888
Funded under: FP7-IDEAS-ERC
Country: Israel

Mid-Term Report Summary - QUCC (Chemistry of the Quantum Kind)

At cold reaction temperatures, close to the absolute zero, reaction dynamics becomes dominated by quantum phenomena. For example, tunneling becomes important and may lead to formation of very long lived collision complexes. The reactants become trapped together for long time and reaction rate might increase by orders of magnitude. In our laboratory we are interested in these cold phenomena and particularly study the importance of the internal molecular degrees of freedom in cold reactions. We have demonstrated that quantum resonances are very sensitive to the molecular rotation of molecular reactant. In the case of Penning ionization reaction of metastable helium with molecular hydrogen we found that the quantum state of molecular rotor is responsible for the nature of interaction. Whereas rotationally ground state hydrogen behaves as an “atom” rotationally excited hydrogen interacts via orientation dependent forces. This allowed us to effectively switch molecular interaction on and off, depending on the internal quantum state of the rotor. In a different experiment we investigated fast reactions that occur with unit probability. Every collision event leads to products and in such a case reaction rate depends only on the long range interaction. Many reactions taking place in the interstellar space follow this trend. We demonstrated that for these fast processes the internal rotation plays a critical role as well. We showed that the most abundant interstellar molecule, hydrogen reacts faster when rotationally excited. We traced this effect to the molecular rotor wavefunction symmetry.
In a different effort our laboratory works towards reaching even lower temperatures with molecular gases where all molecules start occupying a single macroscopic quantum state. In our approach we use fast and cold molecular beams to cool molecules to sub-Kelvin temperatures. We trap and decelerate these fast molecular beams using high magnetic fields. Currently we investigate possible cooling methods that we can apply on trapped molecular clouds that will eventually lead to a formation of molecular Bose-Einstein condensates.

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