A mid-infrared diagnostic for benzene using a tunable difference-frequency-generation laser
AuthorsShakfa, Mohammad Khaled
KAUST DepartmentChemical Kinetics & Laser Sensors Laboratory
Clean Combustion Research Center
Mechanical Engineering Program
Physical Science and Engineering (PSE) Division
Online Publication Date2020-09-16
Print Publication Date2020-09
Embargo End Date2022-09-16
Permanent link to this recordhttp://hdl.handle.net/10754/665391
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AbstractBenzene is a very important molecule in a variety of industrial, environmental, and chemical systems. In combustion, benzene plays an essential role in the formation and growth of polycyclic aromatic hydrocarbons and soot. In this work, a new laser-based diagnostic is presented to make quantitative, interference-free, and sensitive measurements of benzene in the mid-infrared (MIR) region. The diagnostic is based on a widely tunable difference-frequency-generation (DFG) laser system. We developed this laser source to emit in the MIR between 666.54 cm-1 and 790.76 cm-1 as a result of the DFG process between an external-cavity quantum-cascade-laser and a CO2 gas laser in a nonlinear, orientation-patterned GaAs crystal. Benzene measurements were carried out at the peak (673.94 cm-1) of the Q-branch of the v11 vibrational band of benzene. The absorption cross-section of benzene was measured over a range of pressures (4.44 mbar to 1.158 bar) at room temperature. The temperature dependence of the absorption cross-section was studied behind reflected shock waves over 553-1473 K. The diagnostic was demonstrated in a high-temperature reactive experiment of benzene formation from propargyl radicals. The new diagnostic will prove highly beneficial for high-temperature studies of benzene formation and consumption kinetics.
CitationShakfa, M. K., Mhanna, M., Jin, H., Liu, D., Djebbi, K., Marangoni, M., & Farooq, A. (2020). A mid-infrared diagnostic for benzene using a tunable difference-frequency-generation laser. Proceedings of the Combustion Institute. doi:10.1016/j.proci.2020.06.382
SponsorsResearch reported in this publication was funded by the Office of Sponsored Research and King Abdullah University of Science and Technology (KAUST).