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Appui indispensable à la réalisation de nombreuses missions de par la multitude de leurs aptitudes et spécialités, les chiens militaires sont amenés à être projetés en dehors du territoire métropolitain. Cette projection est soumise au respect de nombreuses contraintes logistiques, réglementaires et sanitaires. En fonction des impératifs de la mission, la mise en oeuvre du transport devra être adaptée au moyen logistique employé. Dans le souci de garantir la santé publique, notamment en empêchant l’introduction d’agents pathogènes, il est nécessaire de respecter certaines obligations réglementaires pouvant être le fait du territoire de projection ou de la France lors du retour de l’animal. Enfin, ces mouvements peuvent être l’occasion de la survenue d’affections ou de troubles que le maître de chien doit savoir appréhender et gérer.

The structure and bonding of solid acetonitrile (CH₃CN) films on amorphous silica are studied, and chemical and physical processes under irradiation with 200 keV protons and 250-400 eV electrons are quantified using transmission infrared spectroscopy, reflection-absorption infrared spectroscopy and temperature-programmed desorption, with the assistance of basic computational chemistry and nuclear materials calculations. The thermal desorption profiles are found to depend strongly on the balance between CH₃CN-surface and CH₃CN-CH₃CN interactions, passing from a sub-monolayer regime (binding energy: 35-50 kJ mol⁻¹) to a multilayer regime (binding energy: 38.2±1.0 kJ mol⁻¹) via a fractional order desorption regime characteristic of islanding as the coverage increases. Calculations using the SRIM code reveal that the effects of the ion irradiation are dominated by electronic stopping of incident protons, and the subsequent generation of secondary electrons. Therefore, ion irradiation and electron irradiation experiments can be quantitatively compared. During ion irradiation of thicker CH₃CN films, a cross section for secondary electron-promoted chemical destruction of CH3CN of 4 (±1) × 10⁻¹⁸ cm² was measured, while electron-promoted desorption was not detected. A significantly higher cross section for electron-promoted desorption of 0.82-3.2 × 10⁻¹⁵ cm² was measured during electron irradiation of thinner CH₃CN films, while no chemical products were detected. The differences between the experimental results can be rationalized by recognizing that chemical reaction is a bulk effect in the CH₃CN film, whereas desorption is a surface sensitive process. In thicker films, electron-promoted desorption is expected to occur a rate that is independent of the film thickness; i.e. show zeroth-order kinetics with respect to the surface concentration.

Molecular hydrogen interaction on water ice surfaces is a major process taking place in interstellar dense clouds. By coupling laser detection and classical thermal desorption spectroscopy, it is possible to study the effect of rotation of D(2) on adsorption on amorphous solid water ice surfaces. The desorption profiles of ortho- and para-D(2) are different. This difference is due to a shift in the adsorption energy distribution of the two lowest rotational states. Molecules in J''=1 rotational state are on average more strongly bound to the ice surface than those in J''=0 rotational state. This energy difference is estimated to be 1.4+/-0.3 meV. This value is in agreement with previous calculation and interpretation. The nonspherical wave function J'' =1 has an interaction with the asymmetric part of the adsorption potential and contributes positively in the binding energy.

A first step, before studying the formation of molecules on surfaces at low temperature by recombination of atoms, is a good understanding of the adsorption/desorption mechanisms of the molecules themselves and a correct interpretation of the results of TPD (Thermally Programmed Desorption) experiments. Experimental studies (performed on our newly built experimental setup “FORMOLISM”) of adsorption and desorption of molecular hydrogen and deuterium on an amorphous porous solid water (ASW) ice surface between 10 and 35 K reveal a very efficient isotopic segregation process. The slight difference in the maximum desorption temperature between the two isotopes leads to a preferential coverage of the sites binding more tightly of the ice surface by D2, independent of the gas deposition process history. A statistical model, which takes into account thermodynamic aspects of adsorption sites as well as isotopic competition, is proposed to understand the enhancement of deuterium fractionation. Model results are in very good agreement with the experimental ones. This mechanism could play a key role in chemistry at the surface of interstellar dust grains. It could in particular explain the isotopic enrichment observed in some dark clouds. The next step will be to measure the rovibrational energy of the molecular hydrogen formed on such surfaces using a REMPI‐TOF detection which allows for selective quantum state identification.