title: Measurement of absolute absorption cross sections for nitrous acid (HONO) in the near-infrared region by the continuous wave cavity ring-down spectroscopy (cw-CRDS) technique coupled to laser photolysis.
abstract: Absolute absorption cross sections for selected lines of the OH stretch overtone 2ν(1) of the cis-isomer of nitrous acid HONO have been measured in the range 6623.6-6645.6 cm(-1) using the continuous wave cavity ring-down spectroscopy (cw-CRDS) technique. HONO has been generated by two different, complementary methods: in the first method, HONO has been produced by pulsed photolysis of H(2)O(2)/NO mixture at 248 nm, and in the second method HONO has been produced in a continuous manner by flowing humidified N(2) over 5.2 M HCl and 0.5 M NaNO(2) solutions. Laser photolysis synchronized with the cw-CRDS technique has been used to measure the absorption spectrum of HONO produced in the first method, and a simple cw-CRDS technique has been used in the second method. The first method, very time-consuming, allows for an absolute calibration of the absorption spectrum by comparison with the well-known HO(2) absorption cross section, while the second method is much faster and leads to a better signal-to-noise ratio. The strongest line in this wavelength range has been found at 6642.51 cm(-1) with σ = (5.8 ± 2.2) × 10(-21) cm(2).
authors.affiliation: PhysicoChimie des Processus de Combustion et de l'Atmosphère, Université Lille Nord de France, PC2A CNRS Université Lille 1, UMR 8522, F-59650 Villeneuve d'Ascq, France.
authors.forename: Chaithanya
authors.initials: C
authors.lastname: Jain
authors.forename: Pranay
authors.initials: P
authors.lastname: Morajkar
authors.forename: Coralie
authors.initials: C
authors.lastname: Schoemaecker
authors.forename: Bela
authors.initials: B
authors.lastname: Viskolcz
authors.forename: Christa
authors.initials: C
authors.lastname: Fittschen