Development of a laser-photofragmentation laser-induced fluorescence instrument for the detection of nitrous acid and hydroxyl radicals in the atmosphere

Autor: B. Bottorff, E. Reidy, L. Mielke, S. Dusanter, P. S. Stevens
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Atmospheric Measurement Techniques, Vol 14, Pp 6039-6056 (2021)
Druh dokumentu: article
ISSN: 1867-1381
1867-8548
DOI: 10.5194/amt-14-6039-2021
Popis: A new instrument for the measurement of atmospheric nitrous acid (HONO) and hydroxyl radicals (OH) has been developed using laser photofragmentation (LP) of HONO at 355 nm after expansion into a low-pressure cell, followed by resonant laser-induced fluorescence (LIF) of the resulting OH radical fragment at 308 nm similar to the fluorescence assay by gas expansion technique (FAGE). The LP/LIF instrument is calibrated by determining the photofragmentation efficiency of HONO and calibrating the instrument sensitivity for detection of the OH fragment. In this method, a known concentration of OH from the photo-dissociation of water vapor is titrated with nitric oxide to produce a known concentration of HONO. Measurement of the concentration of the OH radical fragment relative to the concentration of HONO provides a measurement of the photofragmentation efficiency. The LP/LIF instrument has demonstrated a 1σ detection limit for HONO of 9 ppt for a 10 min integration time. Ambient measurements of HONO and OH from a forested environment and an urban setting are presented along with indoor measurements to demonstrate the performance of the instrument.
Databáze: Directory of Open Access Journals
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