Based on optical feedback cavity-enhanced absorption spectroscopy (OF-CEAS) technology, a research team led by Professor Zhang Weijun of the Hefei Institute of Science and Technology (HFIPS) of the Chinese Academy of Sciences (CAS) recently detected hydroxyl radicals. (OH) Wavelength 2.8 μm using a distributed feedback diode laser.
The results are published in Optics Express..
Oh Free radicals It is the most important oxidizer in the atmosphere. The rapid circulation reaction determines the production and removal of major pollutants in the atmosphere. Accurate measurement of OH radicals is very difficult due to their high reactivity, short lifetime and low atmospheric concentration. And it is an important and challenging research topic in the field of atmospheric chemistry today.
“This study provides a new method for direct detection of OH radicals,” said Yang Nana, the lead author of the paper.
She further explained that OF-CEAS can effectively narrow the line width of the laser by feeding it back to the laser using the resonant light of the cavity. In addition, optical self-locking can be achieved, the coupling efficiency between the laser and the cavity can be improved, and high-sensitivity detection can be achieved.
In this study, the team used wavelength modulation to control the optical phase. They use the cavity mode 1f signal demodulated by the lock-in amplifier as an error signal and send it to the proportional integral differential servo controller, laser For tooth decay. Therefore, the system achieved real-time phase locking. The detection sensitivity was about 3 times that of the symmetry analysis method.
OF-CEAS, in combination with Faraday rotation spectroscopy and frequency modulation spectroscopy, can provide a new sensitive approach for the direct detection of OH radicals in the atmosphere.
Nana Yang et al, Optical Feedback Cavity Enhanced Absorption Spectroscopy for OH Radical Detection at 2.8 µm Using DFB Diode Laser, Optics Express (2022). DOI: 10.1364 / OE.456648
Chinese Academy of Sciences
Quote: The first hydroxyl radical detected at a wavelength of 2.8 μm by optical feedback cavity enhanced absorption spectroscopy (April 29, 2022) is https: //phys.org/news/2022-04-hydroxyl-radicals-length- Obtained from April 29, 2022. Optical feedback-cavity-enhanced.html
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Hydroxyl radical first detected at wavelength 2.8 μm by optical feedback cavity enhanced absorption spectroscopy
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