High resolution mass spectrometry for future space missions: comparative analysis of Titan's tholins
Laura Selliez  1, 2@  , Julien Maillard  3, 4@  , Barnabé Cherville  5@  , Thomas Gautier  4@  , Laurent Thirkell  1@  , Bertrand Gaubicher  1@  , Isabelle Schmitz-Afonso  3@  , Carlos Afonso  3@  , Christelle Briois  5@  , Nathalie Carrasco  6, 7@  
1 : Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
Centre National de la Recherche Scientifique : UMR7328
3A, Avenue de la Recherche Scientifique 45071 Orléans cedex 2 -  France
2 : Laboratoire Atmosphères, Milieux, Observations Spatiales
CNRS : UMR8190
11 boulevard d'Alembert Quartier des Garennes 78280 - Guyancourt -  France
3 : Chimie Organique et Bioorganique : Réactivité et Analyse (COBRA)
CNRS : UMR6014
4 : Laboratoire Atmosphères, Milieux, Observations Spatiales
CNRS : UMR8190
11 boulevard d'Alembert Quartier des Garennes 78280 - Guyancourt -  France
5 : Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
CNRS : UMR7328
3A, Avenue de la Recherche Scientifique 45071 Orléans cedex 2 -  France
6 : Laboratoire Atmosphères, Milieux, Observations Spatiales
Centre National de la Recherche Scientifique : UMR8190
11 boulevard d'Alembert Quartier des Garennes 78280 - Guyancourt -  France
7 : Institut Universitaire de France
Ministère de l\'Education nationale, de l’Enseignement supérieur et de la Recherche, Ministère de l\'Éducation nationale, de l’Enseignement supérieur et de la Recherche
Maison des Universités 103 Boulevard Saint-Michel 75005 Paris -  France

Part of Titan's secrets have been revealed by the Cassini-Huygens mission. Among many discoveries, the unexpected detection of positive and negative ions, some of them at very high masses (Waite et al 2007, Coates et al 2007) has shown the surprisingly complex organic chemistry occurring in the exosphere of this unique moon.

In the laboratory, synthesis then analyses of tholins, analogues of Titan's aerosols, help understanding the chemical processes occurring in the atmosphere of Titan. One of the experiments allowing this tholins synthesis is named PAMPRE (Production d'Aérosols en Microgravité par Plasmas REactifs) and produces solid particles in a N2-CH4 gaseous mixture (Szopa et al 2006). Samples studied in this work were produced with an initial amount of 5% of CH4 and 95% of N2.

This tholins analysis was performed with the new high resolution mass analyzer CosmOrbitrap development (Briois et al., 2016, Selliez et al., 2019), based on the OrbitrapTM technology (Makarov 2000), coupled with a commercial Nd-YAG laser at 266 nm, as ionization source (Laser Ablation-CosmOrbitrap). The analysis of the same sample is made with a FTICR equipped with a laser desorption ionization at 355 nm (LDI-FTICR) leading to a challenging comparison as the FTICR is a laboratory benchmark in mass spectrometry.

Significant similarities are shown between both techniques. Species are similarly detected and identified. In addition we also present the formation of clusters ions with the LAb-CosmOrbitrap which allows informative indirect detections about the chemical compounds of tholins such as the detection of HCN assumed to be involved in the polymeric growth of tholins by laboratory ESI-HRMS (High Resolution Mass Spectrometry) studies (Gautier et al., 2014, Pernot et al., 2010).

The capabilities of the LAb-CosmOrbitrap are demonstrated on highly complex organic compounds simulating extraterrestrial matter. This study validates the relevance of a space Laser-CosmOrbitrap mass spectrometer for the future planetary exploration and exobiological space missions.


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