Eur. Phys. J. D 33, 29-33 (2005)
https://doi.org/10.1140/epjd/e2005-00022-0

Pressure broadening parameters of the hydroxyl radical A ²Σ⁺ (υ' = 0) ← X ²Π_3/2 (υ'' = 0) transitions at ca. 308 nm^*

School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Manchester, M60 1QD, UK

Corresponding author: ^a Vasili.Kasiutsich@manchester.ac.uk

Received: 3 November 2004
Revised: 21 December 2004
Published online: 8 February 2005

Abstract

Pressure broadening widths and pressure-induced frequency shifts for the hydroxyl radical Q₁₁([see full textsee full text]), Q₂₁([see full textsee full text]), Q₁₁(2), Q₂₁(2) absorption lines in the A band at ca. 308 nm have been determined in the presence of a variety of gases (N₂, Ar, Ne and He). Hydroxyl radicals were formed using either a microwave discharge or a vacuum ultra-violet photolysis of water vapour and were detected using direct absorption spectroscopy with a bandwidth normalised noise equivalent absorption sensitivity of  Hz^-1/2. A tunable external cavity diode laser at 835 nm and a single-frequency continuous-wave intracavity frequency-doubled diode laser at 488 nm were used to produce tunable continuous-wave light at 308 nm by sum-frequency generation in a  crystal.