Quantitative measurement of transient species using concentration modulation spectroscopy: Take OH as an example

We report the quantitative measurement of transient species by concentration modulation spectroscopy using a mid-infrared laser operating at 2.8 mu m. Transient species were produced by water vapor glow discharge. Direct absorption spectroscopy was used to verify the feasibility of the quantitative measurement of concentration modulation spectroscopy. It was found that concentration modulation spectroscopy was particularly sensitive to excited molecules and fragments molecules produced by parent molecules. Trace OH radical was quantitatively measured using its concentration modulation absorption spectrum with proper calibration.

Automated summary

This paper presents a method for quantitatively measuring transient species using concentration modulation spectroscopy with a mid-infrared laser. The technique was shown to be particularly sensitive to excited and fragmented molecules generated from parent molecules. The study successfully quantitatively measured trace OH radicals using their concentration modulation absorption spectrum with proper calibration.