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Abstract Faraday rotation spectroscopy and absorption spectroscopy are performed simultaneously in a dual comb spectroscopy arrangement with quantum cascade laser combs operating at ∼8μm. The system uses free-running laser combs that provide ∼70 cm−1spectral coverage and ∼2 MHz spectral resolution. Detection of NO2in an equilibrium mixture with N2O4and N2O is used to demonstrate selective measurements of paramagnetic NO2in the presence of spectrally interfering diamagnetic species.
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Time-resolved HO 2 detection with Faraday rotation spectroscopy in a photolysis reactor
Faraday rotation spectroscopy (FRS) employs the Faraday effect to detect Zeeman splitting in the presence of a magnetic field. In this article, we present system design and implementation of radical sensing in a photolysis reactor using FRS. High sensitivity (100 ppb) and time resolvedin situHO2detection is enabled with a digitally balanced acquisition scheme. Specific advantages of employing FRS for sensing in such dynamic environments are examined and rigorously compared to the more established conventional laser absorption spectroscopy (LAS). Experimental results show that FRS enables HO2detection when LAS is deficient, and FRS compares favorably in terms of precision when LAS is applicable. The immunity of FRS to spectral interferences such as absorption of hydrocarbons and other diamagnetic species absorption and optical fringing are highlighted in comparison to LAS.
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- Award ID(s):
- 1903362
- PAR ID:
- 10210160
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Express
- Volume:
- 29
- Issue:
- 2
- ISSN:
- 1094-4087; OPEXFF
- Format(s):
- Medium: X Size: Article No. 2769
- Size(s):
- Article No. 2769
- Sponsoring Org:
- National Science Foundation
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