IMPROVEMENTS IN AND RELATING TO MOLECULAR SEPARATION

摘要

A method of selectively stimulating one molecular component in a mixture is provided. The method involves raising both components to a first excited state with a first pulse of laser radiation, and selectively raising one component to a second excited state with a second pulse of laser radiation of femtosecond duration. The second pulse may be provided at a time after the first pulse equal to an integral number of half periods of the natural resonance period of the selected component and/or when the intranuclear separation is at or close to its maximum, both pulses being of duration very much less than that resonance period. The selectively excited molecule may fluoresce from the second excited state, for example allowing iodine to be detected even in the presence of an oxide of nitrogen. Alternatively, the mixture may comprise isotopes of an element and the selectively excited isotope may then be separated, e.g. deuterium from hydrogen, <129>I2 from <127>I2 or <235>U from <238>U, in molecular form, by a chemical or physical process.