Tech

Hydroxyl radical first detected at wavelength 2.8 μm by optical feedback cavity enhanced absorption spectroscopy

Schematic diagram of an optical feedback cavity enhanced absorption spectroscopy system. Credit: Yang Nana

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.

Hydroxyl radical first detected at wavelength 2.8 μm by optical feedback cavity enhanced absorption spectroscopy

Left: Cavity transmission signal as a function of time recorded by applying a linear current lamp to the diode laser injection current. Right: Enlarged profile showing cavity mode. The dotted line indicates the peak position and divides the cavity mode into left (A) and right (B) parts. Credit: Yang Nana

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.


High-sensitivity detector developed for nitrogen dioxide detection


For more information:
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

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

This document is subject to copyright. No part may be reproduced without written permission, except for fair transactions for personal investigation or research purposes. Content is provided for informational purposes only.



Hydroxyl radical first detected at wavelength 2.8 μm by optical feedback cavity enhanced absorption spectroscopy

Source link Hydroxyl radical first detected at wavelength 2.8 μm by optical feedback cavity enhanced absorption spectroscopy

Show More

Related Articles

Back to top button