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Title: Frequency measurements and self-broadening of sub-Doppler transitions in the v1 + v3 band of C 2H 2

Here, frequency comb-referenced measurements of sub-Doppler laser saturation dip absorption lines in the v1 + v3 band of acetylene near 1:5 μm are reported. These measurements include transitions involving higher rotational levels than previously frequency measured in this band. The accuracy of the measured frequencies is typically better than 10 kHz. Measurements of the observed sub-Doppler line widths as a function of pressure showed that the self pressure-broadening coefficients are about 3.5 times larger than those derived from conventional pressure broadening of unsaturated Doppler-limited spectra. This is attributed to the contribution of velocity-changing collisions to the total dephasing rate in the low pressure sub-Doppler measurements. At higher pressures, when the homogeneous broadening becomes comparable to the typical Doppler shift per elastic collision, the velocity changing collisions cease to contribute significantly to the incremental pressure broadening. Lastly, a time-dependent soft collision model is developed to illustrate the transition between low and high pressure regimes of sub-Doppler pressure-broadening.
Authors:
 [1] ; ORCiD logo [1] ;  [2]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States). Division of Chemistry, Department of Energy and Photon Sciences
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). Division of Chemistry, Department of Energy and Photon Sciences ; Stony Brook Univ., NY (United States). Dept. of Chemistry
Publication Date:
Report Number(s):
BNL-209076-2018-JAAM
Journal ID: ISSN 0021-9606
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 149; Journal Issue: 15; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division; USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1473639
Alternate Identifier(s):
OSTI ID: 1478275

Twagirayezu, Sylvestre, Hall, Gregory E., and Sears, Trevor J.. Frequency measurements and self-broadening of sub-Doppler transitions in the v1 + v3 band of C2H2. United States: N. p., Web. doi:10.1063/1.5047410.
Twagirayezu, Sylvestre, Hall, Gregory E., & Sears, Trevor J.. Frequency measurements and self-broadening of sub-Doppler transitions in the v1 + v3 band of C2H2. United States. doi:10.1063/1.5047410.
Twagirayezu, Sylvestre, Hall, Gregory E., and Sears, Trevor J.. 2018. "Frequency measurements and self-broadening of sub-Doppler transitions in the v1 + v3 band of C2H2". United States. doi:10.1063/1.5047410.
@article{osti_1473639,
title = {Frequency measurements and self-broadening of sub-Doppler transitions in the v1 + v3 band of C2H2},
author = {Twagirayezu, Sylvestre and Hall, Gregory E. and Sears, Trevor J.},
abstractNote = {Here, frequency comb-referenced measurements of sub-Doppler laser saturation dip absorption lines in the v1 + v3 band of acetylene near 1:5 μm are reported. These measurements include transitions involving higher rotational levels than previously frequency measured in this band. The accuracy of the measured frequencies is typically better than 10 kHz. Measurements of the observed sub-Doppler line widths as a function of pressure showed that the self pressure-broadening coefficients are about 3.5 times larger than those derived from conventional pressure broadening of unsaturated Doppler-limited spectra. This is attributed to the contribution of velocity-changing collisions to the total dephasing rate in the low pressure sub-Doppler measurements. At higher pressures, when the homogeneous broadening becomes comparable to the typical Doppler shift per elastic collision, the velocity changing collisions cease to contribute significantly to the incremental pressure broadening. Lastly, a time-dependent soft collision model is developed to illustrate the transition between low and high pressure regimes of sub-Doppler pressure-broadening.},
doi = {10.1063/1.5047410},
journal = {Journal of Chemical Physics},
number = 15,
volume = 149,
place = {United States},
year = {2018},
month = {10}
}

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