TOWARD TWO-COLOR SUB-DOPPLER SATURATION RECOVERY KINETICS IN CN (X, v = 0, J)

Xu, Hong

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https://hdl.handle.net/2142/79473 Copy

Description

Title

TOWARD TWO-COLOR SUB-DOPPLER SATURATION RECOVERY KINETICS IN CN (X, v = 0, J)

Author(s)

Xu, Hong

Contributor(s)

• Dagdigian, Paul
• Hall, Gregory
• Sears, Trevor
• Forthomme, Damien

Issue Date

22-Jun-15

Keyword(s)

Mini-symposium: High-Precision Spectroscopy

Abstract

Collision-induced rotational energy transfer among rotational levels of ground state chem{CN} (X $^{2}$$Sigma$$^{+}$, v = 0) radicals has been probed by saturation recovery experiments, using high-resolution, polarized transient FM spectroscopy to probe the recovery of population and the decay of alignment following ns pulsed laser depletion of selected chem{CN} rotational levels. Despite the lack of Doppler selection in the pulsed depletion and the thermal distribution of collision velocities, the recovery kinetics are found to depend on the probed Doppler shift of the depleted signal. The observed Doppler-shift-dependent recovery rates are a measure of the velocity dependence of the inelastic cross sections, combined with the moderating effects of velocity-changing elastic collisions. New experiments are underway, in which the pulsed saturation is performed with sub-Doppler velocity selection. The time evolution of the spectral hole bleached in the initially thermal chem{CN} absorption spectrum can characterize speed-dependent inelastic collisions along with competing elastic velocity-changing collisions, all as a function of the initially bleached velocity group and rotational state. The initial time evolution of the depletion recovery spectrum can be compared to a stochastic model, using differential cross sections for elastic scattering as well as speed-dependent total inelastic cross sections, derived from ab initio scattering calculations. Progress to date will be reported. Acknowledgments: Work at Brookhaven National Laboratory was carried out under Contract No. DE-AC02-98CH10886 and DE-SC0012704 with the U.S. Department of Energy and supported by its Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

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http://hdl.handle.net/2142/79473

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