Open AccessSensitive and selective detection of OH radicals using Faraday rotation spectroscopy at 28 µm
Author(s) -
Weixiong Zhao,
Gerard Wysocki,
Weidong Chen,
Éric Fertein,
David Le Coq,
Denis Petitprez,
Weijun Zhang
Publication year - 2011
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.19.002493
Subject(s) - faraday effect , spectroscopy , optics , radical , detection limit , materials science , laser , tunable diode laser absorption spectroscopy , absorption spectroscopy , analytical chemistry (journal) , tunable laser , physics , chemistry , magnetic field , organic chemistry , chromatography , quantum mechanics
We report on the development of a Faraday rotation spectroscopy (FRS) instrument using a DFB diode laser operating at 2.8 µm for the hydroxyl (OH) free radical detection. The highest absorption line intensity and the largest gJ value make the Q (1.5) double lines of the 2Π3/2 state (υ = 1 ← 0) at 2.8 µm clearly the best choice for sensitive detection in the infrared region by FRS. The prototype instrument shows shot-noise dominated performance and, with an active optical pathlength of only 25 cm and a lock-in time constant of 100 ms, achieves a 1σ detection limit of 8.2 × 10(8) OH radicals/cm3.