In this thesis, a joint experimental and theoretical investigation of the vector properties that describe the inelastic scattering of a diatomic radical with an atomic collision partner is presented. A particular emphasis is placed on those correlations that include the final rotational angular momentum, j', of the radical. The depolarisation of both NO(A) and OH(A) brought about through collisions with krypton has been studied, providing a measure of the j-j' correlation, where j is the initial rotational angular momentum associated with the diatom. The total depolarisation cross- sections for both collisional disorientation and disalignment have been measured using quantum beat spectroscopy, and modelled theoretically using quasi-classical trajectory (QCT) calculations. The agreement between experiment and theory for NO(A)-Kr is excellent, but is not observed for OH(A)-Kr under thermal conditions. This has been attributed to the importance of electronic quenching in OH(A)-Kr. The depolarisation cross-sections have also been determined at a higher collision energy for OH(A)-Kr where electronic quenching is less significant, and the experimental results are in better agreement with those obtained theoretically. The NO(A)-Kr depolarisation cross-sections fall with increasing rotational quantum number, N, whereas for OH(A)-Kr, they exhibit less of an N dependence. This trend is mirrored in the elastic depolarisation cross-sections, which have also been determined experimentally for OH(A)-Kr. The significantly attractive and anisotropic nature of the OH(A)-Kr potential energy surface (PES) accounts for these observations. The j-j' correlation is extended to include the initial (relative) velocity (k) in a new theoretical treatment of the k-j-j' correlation. The formalism developed is used with the results from the QCT calculations for NO(A)-Kr and OH(A)-Kr to provide further insight into the mechanism of depolarisation in the two systems. Collisions of NO(A) with krypton do not cause significant depolarisation due to their impulsive nature, and the projection of j onto the kinematic apse is conserved. In contrast, collisions of OH(A) with krypton effectively randomise the direction of j, again showing the influence of the anisotropic and attractive nature of the PES. However, the projection of j onto the kinematic apse is still conserved. The inelastic scattering of NO(X) with argon and krypton has also been investigated, using a crossed molecular beam apparatus. The initial Λ-doublet state of the NO(X) was selected using hexapole focussing, and the products of the collision detected using velocity mapped ion imaging. The state to state differential cross-sections (equivalent to the k-k' correlation, where k' is the final relative velocity) have been measured for collisions which conserve the initial spin-orbit level of the NO(X) with krypton. The same parity dependent effects were seen as have been observed previously for NO(X)-Ar. The collision induced alignment (equivalent to the k-k'-j' correlation) of NO(X) as a result of scattering with argon has also been determined experimentally. The results can be explained classically by considering the conservation of the projection of j onto the kinematic apse.

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This thesis presents a joint experimental and theoretical study of a bimolecular collision between OH(A) and H₂ diatoms. The study focuses on the relationship between the initial, <b><i>j</i></b>, and final rotational angular momentum, <b><i>j'</i></b>. This relationship is explored from both a scalar point of view by measuring rotational energy transfer (RET), and a vectorial viewpoint by considering the collisional depolarisation. The experimental technique used in this investigation, Zeeman quantum beat spectroscopy, is first demonstrated by applying it to the determination of the lab-frame orientation of OH(X) photofragments following the photolysis of H₂O₂. The H₂O₂ is photolysed by circularly-polarised light at 248 nm, and Zeeman quantum beat spectroscopy probes the angular momentum orientation as a function of the photofragment spin-rotation level. The results of this experiment are compared with orientation parameters predicted by a simulation that couples the rotation of the parent molecule to the torsional motion during bond cleavage. The calculations from the model agree qualitatively with those from the experiment. The Zeeman quantum beat spectroscopy technique is then used to monitor the evolution of angular momentum polarisation of OH(A) radicals during collisions with H₂. The technique allows for the determination of depolarisation cross sections for oriented and aligned distributions, as a result of collisions with H₂. Alongside this, cross sections for collisional quenching to non-reactive OH(X)+H₂ and reactive H₂O+H products are determined. By resolving the fuorescence with a monochromator the contributions to depolarisation from elastic collisions (the elastic depolarisation cross sections) are measured alongside cross sections for RET. Cross sections for total depolarisation and rotational energy transfer demonstrate only weak dependence on the rotational quantum number of the OH(A) radical, <i>N</i>_OH. Competing quenching processes that fall with <i>N</i>_OH are likely a considerable cause of this weak dependence. Furthermore, the polarisation of the angular momentum of OH(A) is randomised following RET. The elastic depolarisation cross sections make only a small contribution to the depolarisation and fall with increasing <i>N</i>_OH. Collectively these trends have not been seen previously in similar studies on OH(A) collisions with atomic colliders. For the theoretical calculations, a four-atom quasi-classical trajectory (QCT) method has been developed, utilising Lagrangian multipliers to fix the OH(A) and H₂ bonds. The calculations demonstrate that collisions involving the formation of complexes that survive for several rotational periods are prevalent in this collision system, and that these lead to large amounts of depolarisation. The calculations also demonstrate that RET in the H₂ diatom supports higher levels of RET in OH(A) than seen in previous triatomic systems. Additionally, when one diatom is depolarised the accompanying diatom is typically also depolarised. These trends, at least in part, are owed to the highly attractive and anisotropic potential energy surface (PES) describing the interaction. The QCT calculations overestimate the experimentally-measured cross sections by more than a factor of 2. The calculations are adiabatic and do not account for the non-adiabatic activity associated with this collision system, and this is likely one cause of the discrepancies. In an attempt to further account for this overestimation, alternative angular momentum binning approaches for the QCT calculations are developed, but with limited success. Further exploration of the topology of the PES used in the calculations suggests that inadequacies in this surface are a major contributor to the discrepancies.

Le Lebanese Atomic Energy Commission (LAEC) poursuit un programme de développement des techniques analytiques pour compléter l’analyse par faisceau d’ions (IBA). Il a décidé de s’équiper d’un spectromètre de masse couplée à l’imagerie 2D puis récemment 3D avec l’acquisition d’un spectromètre de masse IONTOF V™ équipé de deux colonnes ioniques délivrant des faisceaux d’agrégats de bismuth et d’argon. Dans ce cadre, mon sujet de thèse a porté sur l'optimisation de l’instrument nouvellement acquis pour l’analyse d’échantillons contenant des composés organiques. Les premiers sujets de recherche sont la mise au point du protocole d’analyse quantitative de médicaments en utilisant la technique « cluster-SIMS-imaging » et l’analyse de la météorite Paris pour localiser la matière organique et déterminer sa composition. Dans les deux cas une approche multi-technique a été utilisée : IBA au LAEC, µ-Raman et µ-IR autour des équipements de Soleil et µPIXE réalisée auprès de l’accélérateur AGLAE (Centre de recherche et de restauration des musées de France, C2RMF).L’analyse de médicaments a été initiée au Liban en collaboration avec un fabricant local de produits pharmaceutiques (Mediphar Laboratories) dans le but d’établir de nouveaux procédés de contrôle qualité de produits finis. Mon étude a montré la complexité du dosage de médicament due à la présence de plusieurs molécules actives (Principe Actif, PA) et de substances organiques et minérales inactives (excipients) mélangées dans des conditions secrètes. Les effets de matrice sont dominants et modifient l’émission ionique conduisant à des erreurs systématiques importantes. Cette complexité a été analysée avec l’étude du Fludinium™ possédant deux PAs. Les résultats de cette étude ont permis d’obtenir la première courbe d’étalonnage du rapport des deux PAs et de quantifier ceux-ci dans les conditions du médicament commercial. Le protocole pour effectuer cette courbe d’étalonnage et les contrôles « qualité » ont été déterminés. Ceux-ci incorporeront une analyse en profil pour contrôler l’homogénéité des échantillons et l’obtention d’étalons produits par le fabricant en suivant ses processus de fabrication. En effet, les expériences ont montré que la réalisation du médicament en laboratoire à partir de ses éléments (PAs et excipients) ne donnait pas la même réponse ionique que le médicament commercial. L’analyse de la météorite Paris a été initiée par une collaboration avec une équipe de l’Institut d’Astrophysique Spatial d’Orsay impliquée dans l’exobiologie et la recherche des premières molécules pré-biotiques dans des échantillons extraterrestres. Le but des recherches est de caractériser la matière organique représentant quelques pourcents en poids dans une matrice minérale complexe, sans utiliser des méthodes chimiques pouvant induire une modification de ces molécules. Cette étude a démontré l’intérêt de l’approche multi-technique centrée autour de la spectrométrie de masse couplée à l’imagerie ionique pour déterminer les éléments principaux de la matrice minérale et organique. L’analyse par µPIXE avec une cartographie micrométrique a permis d’attribuer les distributions d’ions moléculaires et agrégats des spectres de masse aux différents composés minéraux. Ces attributions se poursuivent avec la constitution d’une base de données de spectres de référence. La composante organique a été extraite et les premières hypothèses de composition ont été envisagées autour des HAPs (Hydrocarbure Aromatique Polycyclique), MOI (Matière Organique Insoluble) et analogues de carbone amorphe produits par irradiation UV de glaces dont les compositions en gaz représentent différentes hypothèses pour les nuages interstellaires. Les protocoles d’analyses multi-techniques établis (incorporant un suivi de l’échantillon par spectrométrie de masse et imagerie ionique) permettent le démarrage d’analyse d’autres échantillons extra-terrestres collectés sur terre ou dans l’espace. / The Lebanese Atomic Energy Commission (LAEC) is incorporated in a development program of the analytical techniques in order to complete the Ion Beam Analysis (IBA). It was decided to get a mass spectrometer coupled to 2D and recently to 3D imaging, by acquiring an ION TOFVTM system equipped with two ionic columns delivering bismuth and argon cluster beams.In this context, my thesis is focused on the optimization of the instrument, recently purchased, for the analysis of samples containing organic compounds. The first subjects of research are the development of a protocol for quantitative analysis of drugs using the « cluster-SIMS-imaging » technique and the Paris meteorite analysis to determine its composition and to localize the organic matter. In the last case a multi-techniques approach was used : IBA in LAEC, µ-Raman et µ-IR around the Soleil synchrotron equipments and µPIXE carried with the AGLAE accelerator (Centre de recherche et de restauration des musées de France, C2RMF).The drug analysis was initiated in Lebanon in collaboration with a local pharmaceutical manufacturer (Mediphar Laboratories) in order to establish new processes for quality control of the final products. My study showed the complexity of the drug quantification which is due to the presence of several active ingredients (AI) and inactive organic and minerals components (excipients) mixed in secret conditions. Matrix effects are dominant and modify the ionic emission leading to significant systematic errors. This complexity has been analyzed with the study of FludiniumTM with two active ingredients. The results of this study allowed to obtain the first calibration curves of the ratio between the two AIs and to quantify them in the commercial drug. The protocol to perform the calibration curve and the « quality» controls were determined. These incorporate a profile analysis to control the homogeneity of the samples and the obtaining standards produced by the pharmaceutical manufacturer following the same process used for the commercial drug. Indeed, the experiments have shown that the preparation of the drug in the laboratory from its elements (AIs and excipients) doesn’t give the same ionic emission as for the commercial drug.The Paris meteorite analysis was initiated by a collaboration with the Institut d’Astrophysique Spatiale d’Orsay team involved in the exobiology and the research of the first prebiotic molecules in the extraterrestrial samples. The work objective is to characterize the organic matter representing few percents in mass in a complex mineral matrix, without any chemical extraction that can induce a modification of these molecules. This study has demonstrated the interest of the multi-techniques approach centered on the mass spectrometry coupled to the ionic imaging for the determination of the main mineral and organic elements of the matrix. µPIXE analysis coupled to the micrometric mapping permits to attribute the distribution of molecular ions and clusters of the mass spectra with different mineral compounds. These attributions continue with the creation of the data base of standard spectra. The organic component was determined and the first hypotheses were considered concerning PAHs (Polycyclic Aromatic Hydrocarbon), IOM (Insoluble Organic Matter) and analogues of amorphous carbon produced par UV irradiation of ices with a gas composition representing different hypotheses for the interstellar clouds. The establish protocols for multi-techniques (incorporating a follow of the sample by mass spectrometry and ion imaging) permits to start the analysis of other extra terrestrial samples collected on earth or in space.