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More information on René Descartes

  Descartes prizes

Aims and Objectives of the Descartes Prizes

The Descartes Prizes are among the activities supported under the European Commission's Seventh Framework Programme, within the Research Directorate Science and Society.

Science Communication Prize

  • Chemistry Close to Absolute Zero

  • This ambitious project, led by Bertrand Rowe in Rennes and Ian Smith in Birmingham, was to pioneer the study of chemical reactions down to extremely low temperatures.

    To carry out such measurements on reactions in the gas-phase, it is necessary to keep the species from solidifying at temperatures well below their freezing points. This formidable challenge is met by cooling the gas by expansion through a specially shaped nozzle. The resultant jet of gas moves at supersonic speed. Its temperature depends on details of the nozzle design but can be as low as a few degrees above absolute zero. Because the gas strikes no surfaces and condensation within the gas is slow compared with the flow, there is no condensation. Chemical reaction is initiated within this jet of very cold gas, usually by creating a reactive species such as a free radical using a pulsed laser.

    A rich variety of molecular processes were studied in the unique facilities in Birmingham and Rennes, especially many reactions between electrically charged ions and molecules and between electrically neutral radicals and molecules. The results set theoreticians a real challenge. What factors control the rates of these rapid reactions that go still faster as the temperature is lowered?

    Because of their fundamental significance, the Birmingham-Rennes results have generated much interest and excitement. However, their importance extends further - they have had a major impact on the understanding of how molecules might form in the deep recesses of space. About 120 molecules have now been identified in huge astronomical aggregates known as interstellar clouds where the molecules are found in close association with particulate matter - 'interstellar dust'. The temperature and densities are very low in these clouds and it is a fascinating to ask what chemistry synthesises the observed molecules.

    Furthermore, interstellar clouds are the birth-place of stars, as dust and molecules are pulled together by gravity. Understanding molecular formation will help astronomers understand this process of collapse and star formation. The Birmingham-Rennes work at low temperatures has shown that a rich chemistry occurs in interstellar clouds and provides, directly and indirectly, information on what appropriate chemical models should be constructed.

    Much has been achieved in this collaboration but much exciting work in low temperature chemistry lies ahead! Chemistry Close to Absolute Zero: Movie


Descartes Prizes:    2005  2004  2003  2002  2001  2000