Description

As part of the Equipex+ OBS4CLIM project, a collaboration between the ICARE laboratory in Orléans and IGE in Grenoble has led to the development of a highly sensitive optical instrument for the direct measurement of atmospheric radicals (OH, halogenated radicals, Criegee intermediates). This instrument, based on a frequency tripled femtosecond laser coupled with a high-finesse optical cavity, offers a detection limit of ~5 × 10⁶ radicals cm⁻³ for OH radical.
The goal of this PhD is to use this innovative instrument in the HELIOS atmospheric simulation chamber (labeled as a CNRS National Instrument within ACTRIS-France and ACTRIS-Europe) to study key reaction kinetics for tropospheric chemistry, particularly those involving the OH radical and Criegee intermediates.

Skills required

• Education: Master’s degree in atmospheric chemistry, environmental sciences, analytical chemistry, or physics/optics. • Skills: o Knowledge of atmospheric chemistry, spectroscopy, and laboratory instrumentation. o Interest in experimental work and data analysis. o Ability to work in a team and in an interdisciplinary environment. • Languages: French and English (scientific level).

Bibliography

Références :
Barbero, A., Grilli, R., Savarino, J., 2025. Mécanismes chimiques responsables de la capacité oxydante de l’atmosphère en Antarctique. La Météorologie 129, 26–33. https://doi.org/10.37053/lameteorologie-2025-0033
Donahue, N.M., Drozd, G.T., Epstein, S.A., Presto, A.A., Kroll, J.H., 2011. Adventures in ozoneland: down the rabbit-hole. Phys. Chem. Chem. Phys. 13, 10848. https://doi.org/10.1039/c0cp02564j
Fuchs, H., Dorn, H.-P., Bachner, M., Bohn, B., Brauers, T., Gomm, S., Hofzumahaus, A., Holland, F., Nehr, S., Rohrer, F., Tillmann, R., Wahner, A., 2012. Comparison of OH concentration measurements by DOAS and LIF during SAPHIR chamber experiments at high OH reactivity and low NO concentration. Atmos. Meas. Tech. 5, 1611–1626. https://doi.org/10.5194/amt-5-1611-2012
Grilli, R, Alrahman, C.A., Ventrillard, I., Kassi, S., Romanini, D., 2012. Cavity-enhanced multiplexed comb spectroscopy down to the photon shot noise. Physical Review A 051804, 1–5. https://doi.org/10.1103/PhysRevA.85.051804
Grilli, R., Legrand, M., Kukui, A., Méjean, G., Preunkert, S., Romanini, D., 2013. First investigations of IO, BrO, and NO2 summer atmospheric levels at a coastal East Antarctic site using mode-locked cavity enhanced absorption spectroscopy. Geophysical Research Letters 40, 791–796. https://doi.org/10.1002/grl.50154
Grilli, Roberto, Mejean, G., Kassi, S., Ventrillard, I., Abd-Alrahman, C., Romanini, D., 2012. Frequency Comb Based Spectrometer for in Situ and Real Time Measurements of IO, BrO, NO2, and H2CO at pptv and ppqv Levels. Environmental Science & Technology 10704–10710.
Platt, U., 2002. The Impact of Halogen Chemistry on the Oxidation Capacity of the Troposphere, in: Barnes, I. (Ed.), Global Atmospheric Change and Its Impact on Regional Air Quality. Springer Netherlands, Dordrecht, pp. 67–75. https://doi.org/10.1007/978-94-010-0082-6_11
Thompson, R.L., Montzka, S.A., Vollmer, M.K., Arduini, J., Crotwell, M., Krummel, P.B., Lunder, C., Mühle, J., O’Doherty, S., Prinn, R.G., Reimann, S., Vimont, I., Wang, H., Weiss, R.F., Young, D., 2024. Estimation of the atmospheric hydroxyl radical oxidative capacity using multiple hydrofluorocarbons (HFCs). Atmos. Chem. Phys. 24, 1415–1427. https://doi.org/10.5194/acp-24-1415-2024
Wang, P., Wang, Y., Wang, J., Mellouki, A., Daële, V., Ren, Y., McGillen, M.R., 2025. Development of a Relative Rate Technique to Measure Criegee Intermediate Reactivity. Environ. Sci. Technol. Lett. 12, 842–847. https://doi.org/10.1021/acs.estlett.5c00372

Keywords

Atmosphere, Atmospheric Simulation Chamber, Radicals, Kinetics, Spectroscopy, Instrumentation