Neste trabalho realizamos um estudo do comportamento do momento magnético e do deslocamento isomérico de uma impureza intersticial de Fe em hospedeiros metálicos de valências 4 (Ti, Zr), 3 (Sc, Y). Investigamos também impurezas intersticiais e substitucionais de Mo e Fe em hospedeiros divalentes. Para realizar este estudo fizemos cálculos de estrutura eletrônica utilizando o RS-LMTO-ASA (\"Real Space - Linear Muffin-Tin Orbital - Atomic Spherical Approximation\"), um método de primeiros princípios dentro da aproximação do funcional densidade local, implementado no espaço real. Calculamos o momento magnético no sítio da impureza nos sistemas acima e constatamos que a impureza intersticial de Fe é não magnética nos hospedeiros de valências 4 e 3, e que tanto as impurezas intersticiais como as substitucionais podem apresentar momento magnético nos hospedeiros divalentes. Mostramos que para os sistemas divalentes o momento magnético depende fortemente da relaxação. Os nossos resultados são explicados através de um modelo simples, baseado no modelo de Wolff. Investigamos também o comportamento do deslocamento isomérico no sítio da impureza de Fe nesses vários sistemas. Constatamos que os nossos resultados concordam razoavelmente bem com os dados experimentais e explicam o comportamento das tendências observadas. / In the present work, we have studied the magnetic moments and the behavior of the isomer shift at the interstitial Fe impurity site in Ti, Sc, Zr and Y hosts. We have also investigated interstitial and substitutional Fe and Mo impurities in Ca, Sr and Yb hosts. To perform the calculations, we have used the RS-LMTO-ASA scheme, a first principles method, within the local spin density approximation, implemented in real space. We calculated the magnetic moments at the impurity site in the above systems and all the substitucional impurities are found to be magnetic. The results show that interstitial Fe is non-magnetic in the tri- and tetravalent hosts, but interstitial Fe and Mo impurities could develop local magnetic moment in divalent hosts. \'We show that the magnetic moment at the impurity site in these divalent hosts is strongly dependent on lattice relaxation. The results can be explained using simple arguments based on Wolff model. We have investigated in a systematic way the behavior of the isomer shift of Fe impurities in these systems. We observed that our results are in generally good agreement with experiment and lead to better understanding of the observed trends in terms of the volume occupied by the Fe in each host.

Durant l'irradiation en réacteur la fission des atomes d'actinides entraine la création de grandes quantités de défauts, qui affecte les propriétés physiques et chimiques des matériaux dans le réacteur, en particulier les matériaux combustibles ou de structure. Une des méthodes non destructives pouvant être utilisées pour caractériser les défauts induits par irradiation, vides ou contenant les produits de fission, est la spectroscopie d'annihilation de positons (SAP). Cette technique expérimentale consiste à détecter le rayonnement généré lors de l'annihilation du paire électron-positon dans un échantillon et en déduire les propriétés de la matière étudiée. Les positons peuvent être piégés dans les défauts de type lacunaire dans les solides, et en mesurant leur temps de vie et les distribution de moment du rayonnement d'annihilation, on peut obtenir des informations sur les volumes libres et les environnements chimiques des défauts. Dans ce travail, des calculs de structure électronique des caractéristiques d'annihilation de positons ont été effectués en utilisant la théorie de la fonctionnelle de la densité à deux composants (TCDFT). Pour calculer les distributions de moment rayonnement d'annihilation, nous avons implémenté les méthodes nécessaires dans le code de calcul libre ABINIT. Les résultats théoriques ont été utilités pour contribuer à l'identification des défauts d'irradiation dans deux céramiques nucléaires, le carbure de silicium (SiC) et le dioxyde d'uranium (UO2). / During in-pile irradiation the fission of actinide nuclei causes the creation of large amounts of defects, which affect the physical and chemical properties of materials inside the reactor, in particular the fuel and structural materials. Positron annihilation spectroscopy (PAS) can be used to characterize irradiation induced defects, empty or containing fission products. This non-destructive experimental technique involves detecting the radiation generated during electron-positron annihilation in a sample and deducing the properties of the material studied. As positrons get trapped in open volume defects in solids, by measuring their lifetime and momentum distributions of the annihilation radiation, one can obtain information on the open and the chemical environments of the defects. In this work electronic structure calculations of positron annihilation characteristics were performed using two-component density functional theory (TCDFT). To calculate the momentum distributions of the annihilation radiation, we implemented the necessary methods in the open-source ABINIT program. The theoretical results have been used to contribute to the identification of the vacancy defects in two nuclear ceramics, silicon carbide (SiC) and uranium dioxide (UO2).

A flexible nanofibrous PVDF-BaTiO3 composite material is prepared for impact sensing and biomechanical energy harvesting applications. Dielectric polyvinylidene fluoride (PVDF) and barium titanate (BaTiO3)-PVDF nanofibrous composites were made using the electrospinning process based on a design of experiments approach. The ultrasonication process was optimized using a 2k factorial DoE approach to disperse BaTiO3 particles in PVDF solution in DMF. Scanning electron microscopy was used to characterize the microstructure of the fabricated mesh. The FT-IR and Raman analysis were carried out to investigate the crystal structure of the prepared mesh. Surface morphology contribution to the adhesive property of the composite was explained through contact angle measurements. The capacitance of the prepared PVDF- BaTiO3 nanofibrous mesh was a more than 40% increase over the pure PVDF nanofibers. A comparative study of dielectric relaxation, thermodynamics properties and impact analysis of electrospun polyvinylidene fluoride (PVDF) and 3% BaTiO3-PVDF nanofibrous composite are presented. The frequency dependent dielectric properties revealed micro structural features of the composite material. The dielectric relaxation behavior is further supported by complex impedance analysis and Nyquist plots. The temperature dependence of electric modulus shows Arrhenius type behavior. The observed non-Debye dielectric relaxation in electric loss modulus follows a thermally activated process which can be attributed to a small polaron hopping effect. The particle induced crystallization is supported with thermodynamic properties from differential scanning calorimetric (DSC) measurements. The observed increase in piezoelectric response by impact analysis was attributed to the interfacial interaction between PVDF and BaTiO3. The interfacial polarization between PVDF and BaTiO3 was studied using density functional theory calculations and atomic charge density analysis. The results obtained indicates that electrospinning offers a potential way to produce nanofibers with desired crystalline nature which was not observed in molded samples. In addition, BaTiO3 can be used to increase the capacitance, desired surface characteristics of the PVDF nanofibers which can find potential application as flexible piezoelectric sensor mimicking biological skin for use in impact sensing and energy harvesting applications.

This work presents a theoretical study of stability of phases in selected metallic systems. We propose a model of structural transformations in transition metal disilicides MoSi2, CrSi2, VSi2 and TiSi2 and in Pd thin films grown on cubic substrates W(001) and Nb(001). The obtained results yield the total energy proles for the structural transformations studied, the activation energies needed for each individual transformation and an estimate of the temperature at which the structure can transform. The total energies are calculated by full-potential linearized augmented plane waves (FLAPW) method incorporated in the WIEN2k code. Both generalized gradient approximation (GGA) and local density approximation (LDA) are employed for the exchange-correlation term. It turns out that temperatures corresponding to the activation energies of structural transformations in transition metal disilicides exceed their melting temperatures. Comparing the resulting total energy proles to those obtained by the semiempirical Bond Order interatomic potentials (BOP) substantially helps to adjust the fitting parameters of the BOPs. The estimated temperature of 168 K needed to transform the hcp structure of an innite Pd crystal into the dhcp structure explains the behavior of the Pd thin lm on W(001) and Nb(001) substrates. Pd lms deposited on W(001) substrate and thicker than about 100 monolayers undergo this transformation already at room temperature. Thinner lms need to be annealed at 400 K rst, due to their stronger interaction with the substrate. The difference between the computed result and a real temperature at which the hcp Pd lm transforms its structure to the dhcp can be explained by both the interaction between the lm and the substrate and by the inuence of the domain topology of the lm. Analyzing different models of transformation of the initial hcp Pd structure to the ground state fcc structure, we identied the optimum model that respects the domain topology of the Pd lm.

<p>    </p> <p>Development on instrumentation and algorithms for chemical structure and chemical kinetics are discussed in this thesis. In Chapter 2 and 3, a consensus equilibrium formalism is introduced for the integration of multiple quantum chemical calculations of molecular and electronic structure. In multi-agent consensus equilibrium (MACE), iterative updates in structure optimization are intertwined with the net output, representing an equilibrium balance between multiple computational agents. MACE structure calculations from the integration of multiple low-level electronic structure calculations were compared favorably for small molecules, with results evaluated through comparison with higher level structure (CCSD). Notably, MACE results differed substantially from the average of the independent computational agent outputs, with MACE yielding improved agreement with higher-level CCSD calculations. The primary focus is on the development of the mathematical framework for implementing MACE for molecular and electronic structure determination, these initial preliminary results suggest potential promise for the use of MACE to improve the accuracy of low-level electronic structure calculations through the integration of multiple parallel methods. In Chapter 4 and 5, Fourier- transform fluorescence recovery after photobleaching (FT-FRAP) coupled with periodically comb pattern was demonstrated to monitor the controlled-release mechanisms of microparticles. By monitoring the time-lapse recovery patterns, spatial mobility were decoded in FT domain. Due to the nature of mobility encoded in FT domain, substantial improvements were demonstrated in terms of enhanced signal-to-noise, simplified mathematics, low requirements of sampling, and multiphoton compatibility to probe inside samples. FT-FRAP was able to discriminate and quantify the internal diffusion and exchange to higher mobility in fitting the recovery kinetics within microparticles. Theoretical modeling of exchange and diffusion- controlled release revealed that both RS and RL microparticles exhibited similar exchange decay, with RL having a much higher diffusion decay. The microscopically higher diffusion of RL microparticles is consistent with the dissolution performance of RL microparticles macroscopically. The distinction of controlled release mechanisms provided by FT-FRAP is important to understand and further optimize the design of controlled release systems for GI tract. </p>

In der vorliegenden Diplomarbeit wurden sekundäre Isotopeneffekte auf NMR-chemische Verschiebungen mit ab-initio quantenchemischen Methoden bestimmt. Um die zu erwartenden Fehler verschiedener Methoden abschätzen zu können, wurden die sekundären Isotopeneffekte von Fluor(2-2H1)ethan auf HF, MP2 und CCSD(T)-Niveau mit tripel- und quadrupel-Zeta Basissätzen berechnet. Anhand der Ergebnisse dieser Rechnungen lässt sich zeigen, dass gauche und antiperiplanare Konformere bereits mithilfe von sekundären Isotopenverschiebungen unterschieden werden können, die auf HF/tz2p-Niveau berechnet wurden. Weiterhin wurde untersucht, ob es eine Abhängingkeit des Isotopeneffektes von den Diederwinkeln zwischen Deuterium- und Fluorsubstituenten gibt. Die sekundären Isotopeneffekte auf 19F-NMR-chemische Verschiebungen von exo- und endo-2-Fluornorbornanen mit Deuterium Substituenten in den endo-3, exo-3, syn-7 oder anti-7 Positionen wurden auf HF/tz2p-Niveau berechnet. Es wird gezeigt, dass die berechneten Isotopeneffekte an 2-Fluornorbornanen eine Identifizierung der verschiedenen Stereoisomere erlauben. / In the present Diploma thesis secondary isotope effects on NMR chemical shieldings were determined using ab-initio quantum chemical methods. In order to estimate errors of various methods, secondary isotope effects on fluoro(2-2H1)ethane were calculated at the HF, MP2 and CCSD(T) level of theory using triple- and quadruple zeta basis sets. On the basis of these calculations it can be shown that gauche and antiperiplanar conformers can already be distinguished by their secondary isotope shifts calculated at the HF/tz2p level of theory. Furthermore it was investigated, whether a dependency of the isotope effects on dihedral angles between the deuterium and the fluorine substituent exists. The secondary isotope effects on 19F chemical shifts of exo- and endo-2-fluoronorbornanes with deuterium subsituents in the endo-3, exo-3, syn-7 or anti-7 positions were calculated at the HF/tz2p level. It is shown that the calculated isotope effects of 2-fluoronorbornanes allow to identify various stereoisomers.

Nous présentons des études expérimentales et théoriques de disiliciures alcalino-terreux, le disilane (Si2H6) et du carbone à haute pression. Nous étudions les disiliciures et en particulier le cas d’une phase plane de BaSI2 qui a une structure hexagonale avec des liaisons sp3 entre les atomes de silicium. Cet environnement électronique conduit à un gaufrage de feuilles du silicium. Nous démontrons alors une amélioration de la température de transition supraconductrice de 6 à 8.9 K lorsque les couches de silicium s’aplanissent dans cette structure. Des calculs ab initio basés sur DFT ont guidé la recherche expérimentale et permettent d’expliquer comment les propriétés électroniques et des phonons sont fortement affectés par les fluctuations du flambage des plans de silicium. Nous avons aussi étudié les phases cristallines de disilane à très haute pression et une nouvelle phase métallique est proposé en utilisant les méthodes de prédiction de structure cristalline. Les températures de transition calculées donnant un supraconducteur autour de 20 K à 100 GPa. Ces valeurs sont significativement plus faibles comparées à celles avancées dans la littérature. Finalement, nous présentons des études de structures de carbone à haute pression à travers une recherche de structure systématique. Nous avons trouvé une nouvelle forme allotropique du carbone avec une symétrie Cmmm que nous appelons Z-carbone. Cette phase est prévue pour être plus stable que le graphite pour des pressions supérieures à 10 GPa. Des expériences et simulation de rayon-X et spectre Raman sugèrent l’existence de Z-carbone dans des micro-domaines de graphite sous pression / We present experimental and theoretical studies of sp3 materials, alkaline-earth-metal (AEM) disilicides, disilane (Si2H6) and carbon at high pressure. First, we study the AEM disilicides and in particular the case of a layered phase of BaSi2 which has an hexagonal structure with sp3 bonding of the silicon atoms. This electronic environment leads to a natural corrugated Si-sheets. Extensive ab initio calculations based on DFT guided the experimental research and permit explain how electronic and phonon properties are strongly affected by changes in the buckling of the silicon plans. We demonstrate experimentally and theoretically an enhancement of superconducting transition temperatures from 6 to 8.9 K when silicon planes flatten out in this structure. Second, we investigated the crystal phases of disilane at the megabar range of pressure. A novel metallic phase of disilane is proposed by using crystal structure prediction methods. The calculated transition temperatures yielding a superconducting Tc of around 20 K at 100 GPa and decreasing to 13 K at 220 GPa. These values are significantly smaller than previously predicted Tc’s and put serious drawbacks in the possibility of high-Tc superconductivity based on silicon-hydrogen systems. Third, we studied the sp3-carbon structures at high pressure through a systematic structure search. We found a new allotrope of carbon with Cmmm symmetry which we refer to as Z-carbon. This phase is predicted to be more stable than graphite for pressures above 10 GPa and is formed by sp3-bonds. Experimental and simulated XRD, Raman spectra suggest the existence of Z-carbon in micro-domains of graphite under pressure

(U,Pu)O2 (aussi appelé MOX) est actuellement utilisé comme combustible dans les réacteurs nucléaires à eau pressurisée (REP) avec une teneur massique en Pu d’environ 10 %. Il est également envisagé comme combustible de référence pour les réacteurs à neutrons rapides à caloporteur sodium, avec une teneur massique en Pu d’environ 25 %. En conditions opérationnelles, (U,Pu)O2 est soumis à des réactions de fission qui génèrent une grande quantité de défauts et de produits de fission. Par migration, ces défauts et produits de fission gazeux peuvent s'agréger en nano-cavités, dislocations et bulles de gaz, conduisant à une modification de la microstructure. Une meilleure description du comportement du combustible à l’échelle atomique, notamment des mécanismes élémentaires impliqués dans la diffusion des défauts et des produits de fission, est donc nécessaire pour affiner les modèles utilisés dans les codes de performance des combustibles. Pour l’étude des propriétés de (U,Pu)O2, nous avons effectué des calculs de structure électronique basés sur la méthode DFT+U combinée au contrôle des matrices d’occupation des orbitales corrélées. Des minimisations d’énergie ainsi que la dynamique moléculaire ab initio ont été utilisées. Nous avons étudié dans un premier temps les propriétés du cristal de (U,Pu)O2 pour différentes teneurs en Pu. Nous avons ensuite étudié la stabilité des défauts ponctuels ainsi que les modifications structurales et électroniques induites par ces défauts ponctuels dans (U,Pu)O2 et (U,Ce)O2, matériau utilisé comme simulant de (U,Pu)O2. Enfin, nous avons étudié le piégeage et la solubilité des gaz de fission (Kr, Xe) et de l’hélium dans la matrice de (U,Pu)O2 / (U,Pu)O2 (commonly called MOX) is currently used as nuclear fuel in pressurized water reactors with a Pu content of around 10 wt.%, and is envisaged as the reference fuel in Generation IV sodium fast reactors (SFR) with a Pu content of around 25 wt.%. Under operation, (U,Pu)O2 is submitted to fission reactions which generate a large quantity and variety of point defects, as well as fission products. By migrating, point defects and gaseous fission products can aggregate into nano-voids, dislocations and fission gas bubbles, which lead to the modification of the fuel microstructure. Therefore, a better description of the fuel behaviour at the atomic scale, and especially of the elementary mechanisms involved in the diffusion of point defects and fission products, is necessary to refine the models used in the fuel performance codes used to simulate the behaviour of fuels at the macroscopic scale. We use electronic structure calculations based on the DFT+U method combined with the occupation matrix control scheme (OMC) to investigate (U,Pu)O2 properties for various Pu contents. Static energy minimizations and ab initio molecular dynamics were used. We have first determined bulk structural, electronic and thermodynamics properties of (U,Pu)O2. We then studied the stability of point defects in (U,Pu)O2 and (U,Ce)O2, as well as the structural and electronic modifications induced by these point defects, in (U,Pu)O2 and the common experimental surrogate (U,Ce)O2. Finally, the fission gas (Kr and Xe) and helium (He) trapping and solubility in (U,Pu)O2 matrix are investigated

In der vorliegenden Diplomarbeit wurden sekundäre Isotopeneffekte auf NMR-chemische Verschiebungen mit ab-initio quantenchemischen Methoden bestimmt. Um die zu erwartenden Fehler verschiedener Methoden abschätzen zu können, wurden die sekundären Isotopeneffekte von Fluor(2-2H1)ethan auf HF, MP2 und CCSD(T)-Niveau mit tripel- und quadrupel-Zeta Basissätzen berechnet. Anhand der Ergebnisse dieser Rechnungen lässt sich zeigen, dass gauche und antiperiplanare Konformere bereits mithilfe von sekundären Isotopenverschiebungen unterschieden werden können, die auf HF/tz2p-Niveau berechnet wurden. Weiterhin wurde untersucht, ob es eine Abhängingkeit des Isotopeneffektes von den Diederwinkeln zwischen Deuterium- und Fluorsubstituenten gibt. Die sekundären Isotopeneffekte auf 19F-NMR-chemische Verschiebungen von exo- und endo-2-Fluornorbornanen mit Deuterium Substituenten in den endo-3, exo-3, syn-7 oder anti-7 Positionen wurden auf HF/tz2p-Niveau berechnet. Es wird gezeigt, dass die berechneten Isotopeneffekte an 2-Fluornorbornanen eine Identifizierung der verschiedenen Stereoisomere erlauben. / In the present Diploma thesis secondary isotope effects on NMR chemical shieldings were determined using ab-initio quantum chemical methods. In order to estimate errors of various methods, secondary isotope effects on fluoro(2-2H1)ethane were calculated at the HF, MP2 and CCSD(T) level of theory using triple- and quadruple zeta basis sets. On the basis of these calculations it can be shown that gauche and antiperiplanar conformers can already be distinguished by their secondary isotope shifts calculated at the HF/tz2p level of theory. Furthermore it was investigated, whether a dependency of the isotope effects on dihedral angles between the deuterium and the fluorine substituent exists. The secondary isotope effects on 19F chemical shifts of exo- and endo-2-fluoronorbornanes with deuterium subsituents in the endo-3, exo-3, syn-7 or anti-7 positions were calculated at the HF/tz2p level. It is shown that the calculated isotope effects of 2-fluoronorbornanes allow to identify various stereoisomers.

Mass-selected infrared multiple photon spectroscopy (IRMPD), Fourier transform ion cyclotron resonance (FT-ICR) kinetic experiments, RRKM and electronic structure calculations have been performed in order to propose a complex mechanism involving the formation of the proton-bound dimer of water (H5O2+) from 1,1,3,3-tetrafluorodimethyl ether. It has been found that the reaction is facilitated by a series of sequential exothermic bimolecular ion-molecule reactions. Evidence for the dominant mechanistic pathway involving the reaction of CF2H-O=CHF+, an ion of m/z 99, with water is presented. The primary channel occurs via nucleophilic attack of water on the ion of m/z 99 (CF2H-O=CHF+), to lose formyl fluoride and yield protonated difluoromethanol (m/z 69). Association of a second water molecule with protonated difluoromethanol generates a reactive intermediate which decomposes via a 1,4-elimination to release hydrogen fluoride and yield the proton-bound dimer of water and formyl fluoride (m/z 67). The 1,4-elimination of hydrogen fluoride is found to be strongly supported by the results of both RRKM theory and electronic structure calculations. Lastly, the elimination of formyl fluoride occurs by the association of a third water molecule to produce H5O2+ (m/z 37). The most probable isomeric forms of the ions with m/z 99 and 69 were found using IRMPD spectroscopy and electronic structure theory calculations. Thermochemical information for reactant, transition and product species was obtained using MP2/aug-cc-pVQZ//MP2(full)/6-31G(d) level of theory. Ionic hydrogen bond (IHB) interactions, resulting from the association of ammonia and two of the protonated methylxanthine derivatives, caffeine and theophylline, have been characterized using mass-selected IRMPD and electronic structure calculations at the MP2/aug-cc-pVTZ//B3LYP/6-311+G(d,p) level of theory. It was found that the formation of a proton-bound dimer (PBD) of caffeine and ammonia was elusive under the experimental conditions. The low binding energy of the caffeine and ammonia PBD is responsible for the perceived difficulty in obtaining an IRMPD spectrum. The IRMPD spectrum of the PBD of theophylline and ammonia was obtained and revealed bidentate IHB formation within the complex, which greatly increased the binding energy relative to the most stable isomer of the PBD of caffeine and ammonia. The IRMPD spectra of the protonated forms of caffeine and theophylline have also obtained. The spectrum of protonated caffeine showed the dominant existence of a single isomer, whereas the spectrum of protonated theophylline showed a mixture of isomers. The mixture of isomers of protonated theophylline resulted as a consequence of proton-transport catalysis (PTC) occurring within the PBD of theophylline and ammonia. All calculated harmonic spectra have been produced at the B3LYP/6-311+G(d,p) level of theory with fundamental frequencies scaled by 0.9679; calculated anharmonic spectra have also been provided at the same level of theory and were found to greatly improve the match with the IRMPD spectra obtained in all cases. Ionic hydrogen bond (IHB) interactions, resulting from the association of caffeine and theophylline with their protonated counterparts, forming proton-bound homodimers, have been characterized using mass-selected IRMPD and electronic structure calculations at the MP2/6-311+G(2d,2p)//B3LYP/6-311+G(d,p) level of theory. It is found that the IRMPD spectra of the proton-bound homodimers of caffeine and theophylline are complicated resulting from the existence of several pairs of enantiomers separated by a narrow range of relative Gibbs free energies (298 K) of 15.6 and 18.2 kJ mol-1, respectively. The IRMPD spectrum of the proton-bound homodimer of theophylline is dominated by a unique isomer facilitated by formation of a bidentate IHB. Formation of this interaction lowers the relative Gibbs free energy of the ion to 9.75 kJ mol-1 below that of the most favourable pair of enantiomers. The IRMPD spectrum of the PBD of caffeine is complicated by the existence of at least two pairs of enantiomers with the strong likelihood of the spectral contributions of a third pair existing. The most favourable enantiomeric pair involves the formation of a O-H+⋯O IHB. However, verification of a pair of enantiomeric PBDs containing a N-H+⋯O IHB is also observed in the IRMPD spectrum of the PBD of caffeine due to the presence of three free carbonyl stretching modes located at 1731, 1751 and 1785 cm-1. The mass-selected IRMPD spectra of the sodium cation-bound dimers (SCBD) of caffeine and theophylline also have been obtained. Both the mass-selected IRMPD spectra and electronic structure calculations predict the most likely structure of the SCBDs of caffeine and theophylline to form by an efficient O⋯Na+⋯O interaction between C=O functional groups possessed by each monomer. The frequencies of the C=O-Na+ stretch are found to be nearly identical in the IRMPD spectra for both of the SCBDs of caffeine and theophylline at 1644 and 1646 cm-1, respectively. However, the degenerate free C=O symmetric and asymmetric stretches for the SCBDs of caffeine and theophylline found at 1732 and 1758 cm^(-1), respectively, demonstrating a red-shift for caffeine possibly linked to a steric interaction absent in theophylline. Free rotation about the O⋯Na+⋯O bond is found to greatly decrease the complexity of the IRMPD spectra of the SCBDs of caffeine and theophylline and demonstrates excellent agreement between the IRMPD and calculated spectra. Electronic structure calculations have been done at the MP2(full)/aug-cc-pCVTZ/6-311+G(2d,2p)//B3LYP/6-311+G(d,p) level of theory using the aug-cc-pCVTZ basis set for Na+ and all Na+-interacting heterotatoms, and the 6-311+G(2d,2p) basis set for all non-interacting atoms within the SCBDs, in order to provide accurate electronic energies. Currently, installation and implementation of a pulsed electrospray high pressure ion source mated to an existing high pressure mass spectrometer (HPMS) is underway. The new ion source will greatly increase the range of possibilities for the study of ion-molecule reactions in the McMahon laboratory. One of the unique features of the new design is the incorporation of a gas-tight electrospray interface, allowing for more possibilities than only the study of cluster-ion equilibria involving hydration (H2On⋯S+), where S+ is an ion produced by electrospray. Other small prototypical biological molecules such as amines and thiols can be used without concern for the toxicity of these species. Another unique design feature allows electrosprayed ions to associate with neutral solvent species in an electric field free reaction chamber (RC). This ensures that values of equilibrium constants determined are truly representative of ions in states of thermochemical equilibrium. The existing HPMS in the McMahon laboratory is limited to the study of small volatile organic molecules. The new ion source will permit the exploration of systems involving non-volatile species, doubly charged ions and many biologically relevant molecules such as amino acids, peptides, nucleobases and carbohydrates.