ISSN:
1432-0649
Keywords:
33.80.+h, 33.20.Ea
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract Absorption and dissociation probabilities of CHCl2F and CDCl2F were investigated by a pulsed CO2 laser in the wavenumber region of largest selectivity for deuterium. The absorption of CHCl2F, which is a difference band, can largely be suppressed by cooling. At 200 K and at 920 cm−1 absorption selectivities up to 4000 were found by extrapolation. In the presence of buffer gas, CDCl2F can be multiphoton excited nearly like a linear absorber (“harmonic oscillator”). This is interpreted by a nearly resonant collisional relaxation v7 to v2 and by the smallness of the cross anharmonicity x27. The dissociation selectivityS was 24,000 at natural abundance. Such large values were measured by a chromatographic method.S depends only onp D, the partial pressure of the deuterated species. This dependence is approximately ln S∝p D −1 . It can be rationalized by considering only the average energy transferred to the nonresonant molecules by collisions with CDCl2F. The above functional shape is related to an Arrhenius type law. Comparison with trifluoromethane for D separation shows that CHCl2F has primarily two advantages: its rapid H-D exchange with water and the less stringent requirements of laser energy and pulse length.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00694807
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