Mid-infrared laser-based detection of benzene

Mohammad Khaled Shakfa, Ali Elkhazraji, Marco Marangoni, Aamir Farooq

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations


Benzene (C6H6) is one of the major public health concerns. It is emitted from various natural and anthropogenic sources, like fires and volcanic emissions, petrol service stations, transportation, and the plastics industry. Here, we present our work on developing a new benzene sensor using a widely tunable difference-frequency-generation (DFG) laser emitting between 11.56 and 15 µm (667–865 cm–1). The DFG process was realized between an external-cavity quantum-cascade-laser and a CO2 gas laser in a nonlinear, orientation-patterned GaAs crystal. We obtained the absorption cross-sections of the Q-branch of the ν4 vibrational band of benzene by tuning the wavelength of the DFG laser between 14.79 and 14.93 μm (670–676 cm–1). Benzene sensing measurements were performed near 14.84 µm (673.97 cm–1) with a direct laser absorption spectroscopy scheme. The benzene concentration was varied between ppb and ppm levels. Even with a relatively short optical path-length of 23 cm, our sensor achieved a benzene detection limit of about 10 ppb.
Original languageEnglish (US)
Title of host publicationOptical Sensors 2021
ISBN (Print)9781510643789
StatePublished - Apr 18 2021


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