1. Development of an open-path incoherent broadband cavity-enhanced spectroscopy based instrument for simultaneous measurement of HONO and NO in ambient air.
- Author
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Wu, T., Chen, W., Fertein, E., Cazier, F., Dewaele, D., and Gao, X.
- Subjects
OPTICAL instruments ,SPECTRUM analysis ,NITROUS acid ,NITROGEN dioxide ,LIGHT emitting diodes ,LIGHT absorption ,AIR ,MEASUREMENT - Abstract
We report on the development of an optical instrument based on incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) for simultaneous open-path measurements of nitrous acid (HONO) and nitrogen dioxide (NO) in ambient air using a UV light emitting diode operating at ∼366 nm. Detection limits of ∼430 pptv for HONO and ∼1 ppbv for NO were achieved with an optimum acquisition time of 90 s, determined by an Allan variance analysis. Based on a 1.85 m long high optical finesse open-path cavity, the effective optical path length of 2.8 km was realized in aerosol-free samples or in an urban environment at modest aerosol levels. Such a kilometer long optical absorption is comparable to that achieved in the well established differential optical absorption spectroscopy (DOAS) technology while keeping the instrument very compact. Open-path detection configuration allows one to avoid absorption cell wall losses and sampling induced artifacts. The demonstrated sensitivity and specificity shows high potential of this cost-effective and compact infrastructure for future field applications with high spatial resolution. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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