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Title: Pure-rotational H 2 thermometry by ultrabroadband coherent anti-Stokes Raman spectroscopy

Coherent anti-Stokes Raman spectroscopy (CARS) is a sensitive technique for probing highly luminous flames in combustion applications to determine temperatures and species concentrations. CARS thermometry has been demonstrated for the vibrational Q-branch and pure-rotational S-branch of several small molecules. Practical advantages of pure-rotational CARS, such as multi-species detection, reduction of coherent line mixing and collisional narrowing even at high pressures, and the potential for more precise thermometry, have motivated experimental and theoretical advances in S-branch CARS of nitrogen (N 2), for example, which is a dominant species in air-fed combustion processes. Although hydrogen (H 2) is of interest given its prevalence as a reactant and product in many gas-phase reactions, laser bandwidth limitations have precluded the extension of CARS thermometry to the H 2 S-branch. We demonstrate H 2 thermometry using hybrid femtosecond/picosecond pure-rotational CARS, in which a broadband pump/Stokes pulse enables simultaneous excitation of the set of H 2 S-branch transitions populated at flame temperatures over the spectral region of 0–2200 cm –1. We present a pure-rotational H 2 CARS spectral model for data fitting and compare extracted temperatures to those from simultaneously collected N 2 spectra in two systems of study: a heated flow and a diffusion flamemore » on a Wolfhard-Parker slot burner. From 300 to 650 K in the heated flow, the H 2 and N 2 CARS extracted temperatures are, on average, within 2% of the set temperature. For flame measurements, the fitted H 2 and N 2 temperatures are, on average, within 5% of each other from 300 to 1600 K. In conclusion, our results confirm the viability of pure-rotational H 2 CARS thermometry for probing combustion reactions.« less
Authors:
 [1] ; ORCiD logo [1] ;  [1] ;  [1]
  1. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Publication Date:
Report Number(s):
SAND-2018-10035J
Journal ID: ISSN 0021-9606; 667836
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 146; Journal Issue: 22; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1473952
Alternate Identifier(s):
OSTI ID: 1363700

Courtney, Trevor L., Bohlin, Alexis, Patterson, Brian D., and Kliewer, Christopher J.. Pure-rotational H2 thermometry by ultrabroadband coherent anti-Stokes Raman spectroscopy. United States: N. p., Web. doi:10.1063/1.4984083.
Courtney, Trevor L., Bohlin, Alexis, Patterson, Brian D., & Kliewer, Christopher J.. Pure-rotational H2 thermometry by ultrabroadband coherent anti-Stokes Raman spectroscopy. United States. doi:10.1063/1.4984083.
Courtney, Trevor L., Bohlin, Alexis, Patterson, Brian D., and Kliewer, Christopher J.. 2017. "Pure-rotational H2 thermometry by ultrabroadband coherent anti-Stokes Raman spectroscopy". United States. doi:10.1063/1.4984083. https://www.osti.gov/servlets/purl/1473952.
@article{osti_1473952,
title = {Pure-rotational H2 thermometry by ultrabroadband coherent anti-Stokes Raman spectroscopy},
author = {Courtney, Trevor L. and Bohlin, Alexis and Patterson, Brian D. and Kliewer, Christopher J.},
abstractNote = {Coherent anti-Stokes Raman spectroscopy (CARS) is a sensitive technique for probing highly luminous flames in combustion applications to determine temperatures and species concentrations. CARS thermometry has been demonstrated for the vibrational Q-branch and pure-rotational S-branch of several small molecules. Practical advantages of pure-rotational CARS, such as multi-species detection, reduction of coherent line mixing and collisional narrowing even at high pressures, and the potential for more precise thermometry, have motivated experimental and theoretical advances in S-branch CARS of nitrogen (N2), for example, which is a dominant species in air-fed combustion processes. Although hydrogen (H2) is of interest given its prevalence as a reactant and product in many gas-phase reactions, laser bandwidth limitations have precluded the extension of CARS thermometry to the H2 S-branch. We demonstrate H2 thermometry using hybrid femtosecond/picosecond pure-rotational CARS, in which a broadband pump/Stokes pulse enables simultaneous excitation of the set of H2 S-branch transitions populated at flame temperatures over the spectral region of 0–2200 cm–1. We present a pure-rotational H2 CARS spectral model for data fitting and compare extracted temperatures to those from simultaneously collected N2 spectra in two systems of study: a heated flow and a diffusion flame on a Wolfhard-Parker slot burner. From 300 to 650 K in the heated flow, the H2 and N2 CARS extracted temperatures are, on average, within 2% of the set temperature. For flame measurements, the fitted H2 and N2 temperatures are, on average, within 5% of each other from 300 to 1600 K. In conclusion, our results confirm the viability of pure-rotational H2 CARS thermometry for probing combustion reactions.},
doi = {10.1063/1.4984083},
journal = {Journal of Chemical Physics},
number = 22,
volume = 146,
place = {United States},
year = {2017},
month = {6}
}