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PhD student to develop of a CHON+PS chemical scheme validated at high temperatures with applications in planetology.

This offer is available in the following languages:
Français - Anglais

Date Limite Candidature : jeudi 9 décembre 2021

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General information

Reference : UMR7583-GENTUA-033
Workplace : CRETEIL
Date of publication : Thursday, November 18, 2021
Scientific Responsible name : Olivia Venot
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 January 2022
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

Within the ANR project “EXACT (EXoplanetary Atmospheric Chemistry at high Temperature)”, the hired PhD candidate will develop a comprehensive CHON+PS scheme and will apply this newly developed scheme to the study of exoplanetary atmospheres, using a kinetic model.
During the first part of the PhD (18 months), the student will develop the CHON+PS scheme, starting from our most up-to-date CHON scheme (Venot+2020). The scheme will be validated through experimental measurements over a large range of pressures (0.01-500 bars) and temperatures (300-2500 K). This development will be performed at LRGP with internationally-recognized experts in experimental and modelling study of combustion kinetics. During the second part of the PhD (18 months), the student will apply the newly developed scheme to the study of planetary atmospheres, using a kinetic model. This work will be performed at LISA with experts in modeling of (exo)planetary atmospheres.
The PhD student will be co-supervised by Olivia Venot at LISA and Baptiste Sirjean at LRGP.

The primary tasks of the PhD fellow are:
- Bibliographical work
- Drive the development and validation of CHON+PS kinetic models
- Develop methods, using computational chemistry, to calculate and tabulate gas-phase rate constants
- Adapt the existing chemical kinetic code to the newly developed scheme
- Develop atmospheric models for various exoplanets and study the chemical composition
- Evaluate the detectability of the new S- and P-species on synthetic spectra
- Writing of scientific articles and thesis and disseminate research results at conferences and seminars.

Work Context

To learn more about the fascinating new worlds of exoplanets, several space telescopes have been designed, such as the JWST (James Webb Space Telescope, launch in October 2021) and Ariel (Atmospheric Remote-sensing Infrared Exoplanet Large Survey, launch in 2029). The broad wavelength coverage and high-sensitivity of the instruments on-board these telescopes will allow us to extract much more information from their data than what has been possible so far, leading to numerous breakthroughs. However, these breakthroughs will be possible only if the models used to interpret the high-resolution observations are robust and reliable. In particular, photo-thermochemical models calculate the chemical composition of exoplanet atmospheres, taking into account the particular chemistry occurring in these media and the effect of disequilibrium processes. The main ingredient of these models, the chemical scheme has to be specifically tailored for their extreme conditions, that is to say very high temperatures and pressures. Thanks to a close collaboration between the Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA) and the Laboratoire Réactions et Génie des Procédés (LRGP), we are the only team in the world capable of providing highly reliable chemical schemes validated over combustion experiments (Venot+2012, 2015, 2020). These schemes, containing Carbon, Hydrogen, Oxygen, and Nitrogen species (CHON) are made available to the community through the KIDA Database and regularly downloaded. However, for a more reliable simulation of exoplanet atmospheric composition, significant improvements are still required: Sulfur- and Phosphorous-bearing molecules can affect the observations of exoplanets' atmospheres and thus need to be incorporated in atmospheric models that are used to analyze them.
Within the ANR project “EXACT (EXoplanetary Atmospheric Chemistry at high Temperature)”, the hired PhD candidate will develop a comprehensive CHON+PS scheme and will apply this newly developed scheme to the study of exoplanetary atmospheres, using a kinetic model.

Additional Information

The candidate will be assigned to the LISA (Laboratoire Interuniversitaire des Systèmes Atmosphériques), UMR CNRS 7583 is a mixed research laboratory between Paris-Est Créteil University (UPEC), Université de Paris (UP) and CNRS. It is a component of the Observatory of Sciences of the Universe EFLUVE and of Institut Pierre Simon Laplace (IPSL), a Federation of 6 research laboratories working on environment and climate in the Paris region.
The main research themes in LISA relate to the understanding of the functioning of terrestrial and planetary atmospheres and of the impacts related to the changes of the atmospheric composition due to human activities. The methods used are based on direct observations in the atmosphere, on experimental simulations performed in the laboratory and on various numerical modeling approaches.
The candidate will also be required to work at the Laboratory Reactions and Process Engineering (LRGP) is a Joint Research Unit of the CNRS and the University of Lorraine. It is located in Nancy, France's second biggest student city. It is mainly located in the city center, in the premises of the National School of Chemical Industries of Nancy (ENSIC). The research lab is a leading chemical and process engineering laboratory in France and in the world. The PhD candidate will work within the Radical Kinetics Group, which has an international recognized expertise in combustion kinetics, both on the experimental and modelling sides.

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