Improving the accuracy and precision of broadband optical cavity measurements.

Authors:
Jun Chen
Jun Chen
College of Pharmacy
Tucson | United States
Shuaishuai Yu
Shuaishuai Yu
b School of Laboratory Medicine and Life Science
Phoenix | United States
Hartmut Herrmann
Hartmut Herrmann
Université de Lyon
France
Dean S Venables
Dean S Venables
National University of Ireland

Spectrochim Acta A Mol Biomol Spectrosc 2019 Jul 10;218:178-183. Epub 2019 Apr 10.

School of Chemistry & Environmental Research Institute, University College Cork, Cork, Ireland; Atmospheric Chemistry Department (ACD), Leibniz Institute for Tropospheric Research (TROPOS), 04318 Leipzig, Germany. Electronic address:

Most extinction measurements require a stable light source to attain high precision and accuracy. Here, we present a convenient approach to normalize light source intensity in broadband optical cavity measurements. In the absence of sample extinction, we show that the in-band signal - the high finesse spectral region of the optical cavity in which sample extinction is measured with high sensitivity - is strongly correlated with the out-of-band signal. The out-of-band signal is insensitive to sample extinction and can act as a proxy for light source intensity. This normalization approach strongly suppressed in-band intensity changes in two incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) instruments with dissimilar light sources and optical cavity properties. Intensity fluctuations in an arc lamp system were suppressed by a factor of 7 to 16 and in the LED spectrometer by a factor of 10. This approach therefore improves the accuracy and precision of extinction measurements where either property is limited by the light source stability.

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Source
http://dx.doi.org/10.1016/j.saa.2019.04.015DOI Listing
July 2019

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