TY - JOUR
T1 - Time-domain modelling and thermometry of the CH4 ν1 Q-branch using hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering
AU - Chen, Timothy Y.
AU - Kliewer, Christopher J.
AU - Goldberg, Benjamin M.
AU - Kolemen, Egemen
AU - Ju, Yiguang
N1 - Funding Information:
We contribute this paper to celebrate Professor Ronald K. Hanson's legacy in laser diagnostics and chemical kinetics. This material is based upon work supported by the U.S. Department of Energy (DOE), Office of Science, Office of Workforce Development for Teachers and Scientists, Office of Science Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education (ORISE) for the DOE under contract number DE-SC0014664. CJK and BMG were supported by the Office of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences, U.S. Department of Energy. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc. for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the US DOE or the US Government. YJ would like to thank the funding support of DOE Plasma Science Center (DE-SC0020233), NETL UCFER (DE-FE0026825), and National Science Foundation grants (CBET-1903362 and NSF-EFRI CBET-2029425). TYC was partially supported by the Program in Plasma Science and Technology at Princeton University Fellowship (PPST). TYC, EK, and YJ acknowledge the support of ExxonMobil through its membership in the Princeton E-ffiliates Partnership of the Andlinger Center for Energy and the Environment. The simulations presented in this article were performed on computational resources managed and supported by the Princeton Institute for Computational Science and Engineering and the Office of Information Technology at Princeton University. We thank Brian D. Patterson for his technical assistance in setting up the furnace and cell for the heated CH4 measurements. We also thank Dr. Thomas Butterworth for providing the CH4 Raman transition line list used in this work.
Publisher Copyright:
© 2020
PY - 2021/2
Y1 - 2021/2
N2 - We present time-domain measurements and modelling of the CH4ν1 vibrational Q-branch, as well as simultaneous temperature acquisition from the CH4 and N2 vibrational Q-branches using broadband hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS). Accurate measurements with fs/ps CARS require knowledge of the time-domain response of the probed molecule at different temperatures and pressures. In this work, a fs/ps CARS model was developed for the CH4ν1 Q-branch and validated using time-resolved probe delay scans at pressures between 70 and 600 Torr and temperatures between 295 and 1000 K. A simplified modified exponential energy gap model was used to determine the linewidths of the Raman transitions within the Q-branch. Total Q-branch linewidths for the entire explored parameter space were also determined from the probe delay scans. This enabled quantitative measurements of CH4 with fs/ps CARS as well as the temperature through the hot bands of the CH4ν1 Q-branch. With a broadband fs laser pulse in a two-beam phase matching scheme, the N2 Q-branch and CH4ν1 Q-branch were simultaneously measured in a heated cell, and the temperatures from each molecule's spectra was evaluated. The fitted temperatures corresponded well with differences ranging from 4 to 17%. It was also shown that exchanging 90% of CH4 for N2 or Ar at 295 K and 500 Torr did not significantly impact the normalized time-domain signal prior to a 100 picosecond probe delay. Spatially resolved one-dimensional (1-D) thermometry using the CH4 Q-branch was also demonstrated with an imaged spatial resolution of 40 µm. With the developed model, 1-D quantitative measurements of CH4 concentration and temperature can be measured with time resolution of tens of picoseconds.
AB - We present time-domain measurements and modelling of the CH4ν1 vibrational Q-branch, as well as simultaneous temperature acquisition from the CH4 and N2 vibrational Q-branches using broadband hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS). Accurate measurements with fs/ps CARS require knowledge of the time-domain response of the probed molecule at different temperatures and pressures. In this work, a fs/ps CARS model was developed for the CH4ν1 Q-branch and validated using time-resolved probe delay scans at pressures between 70 and 600 Torr and temperatures between 295 and 1000 K. A simplified modified exponential energy gap model was used to determine the linewidths of the Raman transitions within the Q-branch. Total Q-branch linewidths for the entire explored parameter space were also determined from the probe delay scans. This enabled quantitative measurements of CH4 with fs/ps CARS as well as the temperature through the hot bands of the CH4ν1 Q-branch. With a broadband fs laser pulse in a two-beam phase matching scheme, the N2 Q-branch and CH4ν1 Q-branch were simultaneously measured in a heated cell, and the temperatures from each molecule's spectra was evaluated. The fitted temperatures corresponded well with differences ranging from 4 to 17%. It was also shown that exchanging 90% of CH4 for N2 or Ar at 295 K and 500 Torr did not significantly impact the normalized time-domain signal prior to a 100 picosecond probe delay. Spatially resolved one-dimensional (1-D) thermometry using the CH4 Q-branch was also demonstrated with an imaged spatial resolution of 40 µm. With the developed model, 1-D quantitative measurements of CH4 concentration and temperature can be measured with time resolution of tens of picoseconds.
KW - Coherent anti-Stokes raman scattering
KW - Femtosecond/picosecond CARS
KW - Laser diagnostics
KW - Methane
KW - Thermometry
KW - Ultrafast spectroscopy
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U2 - 10.1016/j.combustflame.2020.11.017
DO - 10.1016/j.combustflame.2020.11.017
M3 - Article
AN - SCOPUS:85097476835
SN - 0010-2180
VL - 224
SP - 183
EP - 195
JO - Combustion and Flame
JF - Combustion and Flame
ER -