| 摘要 |
A method of separating isotopes from polyatomic molecules, in particular <13>C from trifluoromethane HCF3, by applying to the polyatomic molecules in the gas phase two infrared laser beams of different frequencies. The first laser has a frequency appropriate to excite a low overtone transition of a light atom stretch vibration and produce vibrationally pre-excited molecules enriched in the desired isotopes, for instance <13>C. The second laser has a frequency and energy fluence to selectively induce dissociation of the vibrationally pre-excited molecules by infrared multiphoton excitation. The product of the pressure of the molecules and the time-delay of the second laser pulse relative to the first allows collisional vibrational deactivation of a substantial amount of the vibrationally pre-excited molecules containing non-desired isotope(s), like <12>C, before dissociation of the vibrationally excited molecules occurs, while there is no significant collisional vibrational deactivation of pre-excited molecules containing the desired isotope, like <13>C. The dissociation products are hence highly enriched in the desired isotope.
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