Development of a laser-photofragmentation laser-induced fluorescence instrument for the detection of nitrous acid and hydroxyl radicals in the atmosphere
Development of a laser-photofragmentation laser-induced fluorescence instrument for the detection of nitrous acid and hydroxyl radicals in the atmosphere
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DOI：
10.5194/amt-14-6039-2021
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发表时间：
2021-09-16
影响因子：
3.8
通讯作者：
Stevens, Philip S.
中科院分区：
文献类型：
--
作者：
Bottorff, Brandon;Reidy, Emily;Stevens, Philip S.
开发了一种测量大气亚硝酸 (HONO) 和羟基自由基 (OH) 的新仪器，使用 HONO 膨胀到低压池后在 355 nm 处进行激光光碎裂 (LP)，然后在 308 nm 处对所得 OH 自由基碎片进行共振激光诱导荧光 (LIF)，类似于气体膨胀技术的荧光测定 （发格）。通过确定 HONO 的光裂解效率并校准仪器检测 OH 片段的灵敏度来校准 LP/LIF 仪器。在此方法中，用一氧化氮滴定来自水蒸气光解的已知浓度的 OH，以产生已知浓度的 HONO。相对于 HONO 浓度的 OH 自由基片段浓度的测量提供了光裂解效率的测量。 LP/LIF 仪器已证明在 10 分钟积分时间内 HONO 的 1 西格玛检测限为 9 ppt。森林环境和城市环境中 HONO 和 OH 的环境测量以及室内测量结果均展示了仪器的性能。
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 photodissociation 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 1 sigma 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.