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

Chaithanya Jain, Pranay Morajkar, Coralie Schoemaecker, Bela Viskolcz, Christa Fittschen

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Abstract

Absolute absorption cross sections for selected lines of the OH stretch overtone 2ν1 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 H2O2/NO mixture at 248 nm, and in the second method HONO has been produced in a continuous manner by flowing humidified N2 over 5.2 M HCl and 0.5 M NaNO2 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 HO2 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 cm2.

Original languageEnglish
Pages (from-to)10720-10728
Number of pages9
JournalJournal of Physical Chemistry A
Volume115
Issue number39
DOIs
Publication statusPublished - Oct 6 2011

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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