ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The method of infrared–infrared double resonance has been used to record the line shapes of a number of transitions in the 2ν3←ν3 band of 13CH3F by means of an infrared microwave sideband laser spectrometer while the QR(4,3) transition in the ν3 band was being pumped by constant-frequency radiation from a CO2 laser operating on the 9P(32) transition. A double modulation technique was used to eliminate single-resonance effects. The double-resonance line shapes for a series of transitions whose lower state is the (J,3) level in the v3=1 vibrational state show a transferred spike whose width is narrow for J values near 5, but slowly increases as J increases. The transferred spike is superimposed on a component of the line shape that is Gaussian with the expected Doppler width. Evidence for a transferred spike still remains for J=22. By contrast, for K≠3, there is only a Gaussian component for any J, except for J≈5, K=6, for which some evidence for a transferred spike can be seen. If the dominant selection rule for collisionally induced transitions is ΔJ=0,±1, then observation of a transferred spike for J=22 indicates some retention of velocity after as many as 17 collisions. The transferred spikes have been analyzed by a line shape function based on the Keilson–Storer collision kernel and the results have been used to estimate the root-mean-square value of the change in velocity upon collision.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.456827
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