A transportable spectrometer for in situ and local measurements of iodine monoxide at mixing ratios in the 10−14 range

• Published in: Applied Physics Letters
• Main Authors: Méjean, Guillaume, Grilli, Roberto, Abd Alrahman, Chadi, Ventrillard, Irène, Kassi, Samir, Romanini, Daniele
• Format: Article in Journal/Newspaper
• Language: English
• Published: AIP Publishing 2012
• Subjects: Physics and Astronomy (miscellaneous); North West Atlantic
• Online Access: http://dx.doi.org/10.1063/1.4726190; https://pubs.aip.org/aip/apl/article-pdf/doi/10.1063/1.4726190/14248867/251110_1_online.pdf

We present a robust, compact, and transportable instrument that measures the iodine monoxide atmospheric radical at extremely low concentration, down to 40 ppqv (parts per quadrillion by volume, 1:1015). As nitrogen dioxide is strongly absorbed in the same spectral region it could be simultaneously measured down to 4 pptv (parts per trillion by volume, 1:1012). Relying on “mode locked cavity-enhanced absorption spectroscopy,” the instrument makes use of a free-running commercial femtosecond Titane Saphir laser. We demonstrate that this multiplex detection scheme provides shot noise limited spectra for acquisition times as long as 5 min. Moreover, this instrument is very versatile as it can be potentially tuned from the infrared to the ultraviolet (1080-340 nm) to reach various molecular absorptions. It has been recently deployed at the Station Biologique de Roscoff on the North West Atlantic coast of France.