A5091325069- Advanced Combustion Engine Technologies
- Spectroscopy and Laser Applications
- Combustion and flame dynamics
- Combustion and Detonation Processes
- Laser Design and Applications
- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Rocket and propulsion systems research
- Gas Dynamics and Kinetic Theory
- Atmospheric and Environmental Gas Dynamics
- Advanced Chemical Physics Studies
- Laser-induced spectroscopy and plasma
- Energetic Materials and Combustion
- Advanced X-ray and CT Imaging
- Chemical Thermodynamics and Molecular Structure
- Diamond and Carbon-based Materials Research
- Ocular and Laser Science Research
- Thermal and Kinetic Analysis
- Mass Spectrometry Techniques and Applications
- Advanced Optical Sensing Technologies
- Covalent Organic Framework Applications
- Radiative Heat Transfer Studies
- Polyoxometalates: Synthesis and Applications
- Catalytic Processes in Materials Science
- Biomedical Text Mining and Ontologies
Peking University
2022-2025
Stanford University
2012-2023
State Key Laboratory of Turbulence and Complex Systems
2022
Qingdao National Laboratory for Marine Science and Technology
2022
Temper (United States)
2013-2020
University of Waterloo
1969
We report the first application of cavity-enhanced absorption spectroscopy (CEAS) using a coherent light source for sensitive and rapid gaseous species time-history measurements in shock tube. Off-axis alignment fast scanning laser wavelength were used to minimize coupling noise low-finesse cavity. An gain factor 83 with measurement time resolution 20 µs was demonstrated C2H2 detection near-infrared transition near 1537 nm, corresponding noise-equivalent limit ppm at 296 K 76 906 50 kHz....
We report the use of cavity-enhanced absorption spectroscopy (CEAS) using two distributed feedback diode lasers near 777.2 and 844.6 nm for sensitive, time-resolved, in situ measurements excited-state populations atomic oxygen a shock tube. Here, 1% O2/Ar mixture was shock-heated to 5400-8000 K behind reflected waves. The combined low-finesse cavity, fast wavelength scanning lasers, an off-axis alignment enabled with 10 μs time response low cavity noise. CEAS gain factors 104 142 P35←S520...
The rate constant of the H-abstraction reaction formaldehyde (CH2O) by hydrogen atoms (H), CH2O + H = H2 HCO, has been studied behind reflected shock waves with use a sensitive mid-IR laser absorption diagnostic for CO, over temperatures 1304–2006 K and at pressures near 1 atm. C2H5I was used as an atom precursor 1,3,5-trioxane precursor, to generate well-controlled CH2O/H reacting system. By designing experiments maintain relatively concentrations, current study significantly boosted...
Cavity-enhanced absorption spectroscopy (CEAS) using a mid-infrared DFB quantum-cascade laser is reported for sensitive time-resolved (10 μs) in situ CO measurements shock tube. Off-axis alignment and fast scanning of the wavelength were used to minimize coupling noise low-finesse cavity. An gain factor 91 was demonstrated, which enabled sub-ppm detection sensitivity gas temperatures 1000-2100K 15 cm diameter This substantial improvement compared conventional single-pass measurements, shows...
The oxidation of Ar-diluted stoichiometric CH2O–O2 mixtures was studied behind reflected shock waves over temperatures 1332–1685 K, at pressures about 1.5 atm and initial CH2O mole fractions 500, 1500, 5000 ppm. Quantitative time-resolved concentration histories OH CO (at both v″ = 0 1) were measured by narrow-linewidth laser absorption 306.7 4854 nm, respectively. A time delay observed between the formation 1 states CO, suggesting that kinetically generated primarily in ground state then...
ABSTRACT Polytetrafluoroethylene (PTFE) is widely used in fields such as propellants and flame retardants. However, this still a vacancy of detailed kinetic mechanisms to describe the complete decomposition PTFE gas phase. The current work addresses issue by conducting ab initio calculations for key reactions involved pyrolysis system. potential energy surfaces (PESs) unimolecular bimolecular are determined at DLPNO‐CCSD(T)/cc‐pVTZ//B3LYP‐D3/6–31++G(d,p) level. Rate constants branching...
We report an improved measurement for the rate constant of methane dissociation in argon (CH4 + Ar = CH3 H Ar) behind reflected shock waves. The experiment was conducted using a sub-parts per million sensitivity diagnostic recently developed our laboratory based on ultraviolet cavity-enhanced absorption spectroscopy. high this allowed measurements quantitatively resolved time histories during initial stage CH4 pyrolysis, where reaction system is clean and free from influences secondary...
A direct measurement for the rate constant of acetone dissociation reaction (CH3COCH3 = CH3CO + CH3) was conducted behind reflected shock wave, utilizing a sub-ppm sensitivity CO diagnostic achieved by cavity-enhanced absorption spectroscopy (CEAS). The current experiment eliminated influence from secondary reactions and temperature change investigating clean pyrolysis <20 ppm in argon. For first time, (k1) directly measured over 5.5 orders magnitude with high degree accuracy: k1 (1004-1494...
The formation of electronically excited atomic oxygen was studied behind reflected shock waves using cavity-enhanced absorption spectroscopy. Mixtures 1% O2-Ar were shock-heated to 5400-7500 K, and two distributed-feedback diode lasers near 777.2 844.6 nm used measure time-resolved populations oxygen's 5S° 3S° electronic states, respectively. Measurements compared with simulated population time histories obtained different kinetic models that accounted for thermal nonequilibrium effects: (1)...