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Isotopically selective collisional vibrational energy transfer in CF3H
R Bossart1, O V Boyarkin, A A Makarov
1Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland.
The Journal of Chemical Physics
|February 17, 2007
Summary
Collisional enhancement of isotopic selectivity in infrared multiple photon dissociation (IRMPD) of CF3H is investigated. The study finds that vibrational energy transfer, not just IRMPD, significantly boosts isotopic selectivity, crucial for laser isotope separation.
Area of Science:
- Chemical Physics
- Molecular Spectroscopy
- Isotope Separation
Background:
- Collisionally enhanced isotopic selectivity is observed in infrared multiple photon dissociation (IRMPD) of vibrationally preexcited CF3H.
- Previous work by Boyarkin et al. highlighted this phenomenon, necessitating further mechanistic investigation.
Purpose of the Study:
- To elucidate the mechanism behind collisionally enhanced isotopic selectivity in CF3H IRMPD.
- To determine the contributions of IRMPD and vibrational energy transfer to the observed isotopic selectivity.
Main Methods:
- Measurement of IRMPD yield dependence on time delay between preexcitation and dissociation pulses.
- Analysis of IRMPD yield dependence on initial isotopic composition at various dissociation frequencies.
- Investigation of vibrational energy transfer selectivity between 12CF3H and 13CF3H.
Main Results:
- The collisional increase in isotopic selectivity arises from both IRMPD selectivity and vibrational energy transfer selectivity.
- Vibrational energy transfer exhibits isotopic selectivity, making a major contribution under the experimental conditions.
- Isotopic selectivity in energy transfer is attributed to spectral overlap differences between isotopically distinct CF3H molecules.
Conclusions:
- Collisional effects significantly enhance isotopic selectivity in CF3H IRMPD.
- Vibrational energy transfer plays a dominant role in this enhanced selectivity.
- Understanding these collisional mechanisms is vital for optimizing laser isotope separation processes.
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