Sr Research Engineer, Mechanical Engineering
- Temperature-dependent absorption cross section measurements for propene, 1-butene, cis-/trans-2-butene, isobutene and 1,3-butadiene in the spectral region 8.4-11.7 mu m JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER 2020; 255
- Two-color frequency-multiplexed IMS technique for gas thermometry at elevated pressures APPLIED PHYSICS B-LASERS AND OPTICS 2020; 126 (3)
Dual-comb Spectroscopy for High-temperature Reaction Kinetics
Measurement Science and Technology
View details for DOI 10.1088/1361-6501/ab6ecc
- Calibration-free breath acetone sensor with interference correction based on wavelength modulation spectroscopy near 8.2 mu m APPLIED PHYSICS B-LASERS AND OPTICS 2020; 126 (1)
- Analysis of laser absorption gas sensors employing scanned-wavelength modulation spectroscopy with 1f-phase detection APPLIED PHYSICS B-LASERS AND OPTICS 2020; 126 (1)
Two-temperature Collisional-radiative Modeling of Partially Ionized O2-Ar Mixtures over 8000-10,000 K Behind Reflected Shock Waves.
The journal of physical chemistry. A
The collisional excitation kinetics of atomic oxygen was studied behind reflected shock waves using tunable diode laser absorption spectroscopy. A test gas mixture of 1% O2/Ar was shock-heated to temperatures between 8000 and 10,000 K and pressures between 0.15 and 1 atm. The time evolution of the atomic oxygen population in the 3 s 5S0 state was monitored by laser absorption at 777.2 nm. The measured O(3 s 5S0) population revealed multistage behavior that was not observed in previous measurements over a temperature range of 5300-7200 K. To interpret the multistage behavior, a three-level collisional-radiative model for atomic oxygen excitation kinetics was developed. The model utilized two independent temperatures, that is, heavy particle translational temperature Ttr and electron translational temperature Te, to describe the fundamental rate constants of atomic oxygen excitation because of collisions with heavy particles and electrons, respectively. The heavy particle excitation rate was inferred from the early stage of the measurement to be k(3P →5S0) = 3.4 × 10-27 (T/K)0.5(1.061 × 105 + 2 (T/K)) exp(-1.061 × 105 K/T) ± 50% m3 s-1. The electron impact excitation rate constant of oxygen, electron impact, and heavy particle impact ionization rate constants of Argon were modified in the model to match the experimental population time histories. The modified rate parameters are also reported for the temperature range explored in the current study.
View details for DOI 10.1021/acs.jpca.0c00466
View details for PubMedID 32306734
- R-branch line intensities and temperature-dependent line broadening and shift coefficients of the nitric oxide fundamental rovibrational band JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER 2019; 239
- High-pressure, high-temperature optical cell for mid-infrared spectroscopy JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER 2019; 231: 69–78
- A two-wavelength ethylene-absorption temperature diagnostic MEASUREMENT SCIENCE AND TECHNOLOGY 2019; 30 (3)
Single-Ended Sensor for Thermometry and Speciation in Shock Tubes Using Native Surfaces
IEEE Sensors Journal
View details for DOI 10.1109/JSEN.2019.2903989
- Single-ended mid-infrared laser-absorption sensor for time-resolved measurements of water concentration and temperature within the annulus of a rotating detonation engine PROCEEDINGS OF THE COMBUSTION INSTITUTE 2019; 37 (2): 1435–43
- Mid-infrared laser absorption spectroscopy of NO2 at elevated temperatures JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER 2017; 187: 364-374
- Line intensities and temperature-dependent line broadening coefficients of Q-branch transitions in the v(2) band of ammonia near 10.4 mu m JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER 2016; 175: 90-99
Line intensities and temperature-dependent line broadening coefficients of Q-branch transitions in the v2 band of ammonia near 10.4 μm.
Journal of quantitative spectroscopy & radiative transfer
2016; 175: 90–99
We report measured line intensities and temperature-dependent broadening coefficients of NH3 with Ar, N2, O2, CO2, H2O, and NH3 for nine sQ(J,K) transitions in the ν2 fundamental band in the frequency range 961.5-967.5 cm-1. This spectral region was chosen due to the strong NH3 absorption strength and lack of spectral interference from H2O and CO2 for laser-based sensing applications. Spectroscopic parameters were determined by multi-line fitting using Voigt lineshapes of absorption spectra measured with two quantum cascade lasers in thermodynamically-controlled optical cells. The temperature dependence of broadening was measured over a range of temperatures between 300 and 600 K. These measurements aid the development of mid-infrared NH3 sensors for a broad range of gas mixtures and at elevated temperatures.
View details for PubMedID 29225373
- Quantification of Supersonic Impulse Flow Conditions via High-Bandwidth Wavelength Modulation Absorption Spectroscopy AIAA JOURNAL 2015; 53 (10): 2978-2987
- Hypersonic Scramjet Testing via Diode Laser Absorption in a Reflected Shock Tunnel JOURNAL OF PROPULSION AND POWER 2014; 30 (6): 1586-1594
Fitting of calibration-free scanned-wavelength-modulation spectroscopy spectra for determination of gas properties and absorption lineshapes
2014; 53 (3): 356-367
The development and initial demonstration of a scanned-wavelength, first-harmonic-normalized, wavelength-modulation spectroscopy with nf detection (scanned-WMS-nf/1f) strategy for calibration-free measurements of gas conditions are presented. In this technique, the nominal wavelength of a modulated tunable diode laser (TDL) is scanned over an absorption transition to measure the corresponding scanned-WMS-nf/1f spectrum. Gas conditions are then inferred from least-squares fitting the simulated scanned-WMS-nf/1f spectrum to the measured scanned-WMS-nf/1f spectrum, in a manner that is analogous to widely used scanned-wavelength direct-absorption techniques. This scanned-WMS-nf/1f technique does not require prior knowledge of the transition linewidth for determination of gas properties. Furthermore, this technique can be used with any higher harmonic (i.e., n>1), modulation depth, and optical depth. Selection of the laser modulation index to maximize both signal strength and sensitivity to spectroscopic parameters (i.e., gas conditions), while mitigating distortion, is described. Last, this technique is demonstrated with two-color measurements in a well-characterized supersonic flow within the Stanford Expansion Tube. In this demonstration, two frequency-multiplexed telecommunication-grade TDLs near 1.4 μm were scanned at 12.5 kHz (i.e., measurement repetition rate of 25 kHz) and modulated at 637.5 and 825 kHz to determine the gas temperature, pressure, H2O mole fraction, velocity, and absorption transition lineshape. Measurements are shown to agree within uncertainty (1%-5%) of expected values.
View details for DOI 10.1364/AO.53.000356
View details for Web of Science ID 000330172300007
View details for PubMedID 24514120
- Supersonic Mass-Flux Measurements via Tunable Diode Laser Absorption and Nonuniform Flow Modeling 49th AIAA Aerospace Sciences Meeting / New Horizons Forum and Aerospace Exposition AMER INST AERONAUT ASTRONAUT. 2011: 2783–91