Improvements to a laser-induced fluorescence instrument for measuring SO2 – impact on accuracy and precision

Autor: P. S. Rickly, L. Xu, J. D. Crounse, P. O. Wennberg, A. W. Rollins
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Atmospheric Measurement Techniques, Vol 14, Pp 2429-2439 (2021)
Druh dokumentu: article
ISSN: 1867-1381
1867-8548
DOI: 10.5194/amt-14-2429-2021
Popis: This work describes key improvements made to the in situ laser-induced fluorescence instrument for measuring sulfur dioxide (SO2) that was originally described by Rollins et al. (2016). Here, we report measurements of the SO2 fluorescence emission spectrum. These measurements allow for the determination of the most appropriate bandpass filters to optimize the fluorescence signal, while reducing the instrumental background. Because many aromatic species fluoresce in the same spectral region as SO2, fluorescence spectra were also measured for naphthalene and anisole to determine if ambient SO2 measurements could be biased in the presence of such species. Improvement in the laser system resulted in better tunability, and a significant reduction in the 216.9 nm laser linewidth. This increases the online/offline signal ratio which, in turn, improves the precision and specificity of the measurement. The effects of these improvements on the instrumental sensitivity were determined by analyzing the signal and background of the instrument, using varying optical bandpass filter ranges and cell pressures and calculating the resulting limit of detection. As a result, we report an improvement to the instrumental sensitivity by as much as 50 %.
Databáze: Directory of Open Access Journals
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