A química do selênio é um assunto de crescente interesse devido a sua presença em diversos ambientes químicos, em particular, na atmosfera terrestre. A ausência de estudos sobre espécies relativamente simples contendo 2-4 átomos motivou este projeto, que se concentrou na investigação teórica rigorosa de uma serie de espécies moleculares: SeF, SeCl, SeBr, HSeF, HFSe, HSeCl, HClSe, HSeBr, HBrSe e de vários isômeros na superfície de energia potencial 1[H, S, Se, Cl]. Propriedades espectroscópicas de um conjunto de estados eletrônicos e o calor de formação das moléculas SeF, SeCl e SeBr foram determinados. Juntamente com os novos resultados desta investigação, sugerimos uma revisão e correção de alguns dados teóricos e experimentais da literatura. Aspectos energéticos, estruturais e espectroscópicos associados aos pontos estacionários nas superfícies de energia potencial singleto [H, Se, X], X = F, Cl e Br, e [H, S, Se, Cl] também foram caracterizados, assim como determinados os calores de formação dos isômeros mais estáveis. Barreiras energéticas para os vários processos de isomerização foram estimadas bem como o gasto energético envolvido nas diferentes possibilidades de dissociação dos isômeros mais estáveis. No caso dos sistemas triatômicos ainda estimamos as constantes de velocidade para as reações de isomerizações direta e reversa. Nesse contexto, esperamos que este trabalho possa servir como uma referência para estudos teóricos e experimentais futuros desses sistemas e/ou de outros de complexidade idêntica. / The chemistry of selenium is a subject of increasing interest due to its presence in many chemical enviroments, specially in the Earth\'s atmosphere. The lack of studies of relatively simple species containing 2-4 atoms has motivated this project which was focused on a rigorous theoretical investigation of a series of molecular especies: SeF, SeCl, SeBr, HSeF, HFSe, HSeCl, HClSe, HSeBr, HBrSe, and the isomers on the 1[H, S, Se, Cl] potential energy surface. Spectroscopic properties of a set of electronic states and the heat of formation of SeF, SeCl, and SeBr were determined. Along with the new results from this investigation, we showed that some theoretical and experimental data reported in the literature be revised and corrected. Energetic, structural, and spectroscopic aspects associated with the stationary points on the singlet potential energy surfaces [H, Se, X], X = F, Cl e Br, and [H, S, Se, Cl] were also characterized, and the heats of formation of the most stable isomers evaluated. Energetic barriers for the various processes of isomerization were estimated, as well as the energy involved in the dierent possibilities of dissociation of the most stable isomers. In the case of triatomic systems, we still estimated the rate constants for the direct and reverse reactions. In this context, we expect that this work should serve as reference in future theoretical and experimental studies on these systems and/or others of similar complexity

Orientador: José de Alencar Simoni / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-25T19:40:09Z (GMT). No. of bitstreams: 1 Martins_JoseRobertoSerra_M.pdf: 2469226 bytes, checksum: cd14cc6ad348a55b155eac21db7817f4 (MD5) Previous issue date: 2014 / Resumo: Experimentos interdisciplinares constituem importante instrumento de ensino/aprendizagem. Partindo-se de um roteiro estruturado, realizou-se uma série de ensaios com o Lançador Termodinâmico de Projéteis (LTP). Os resultados dos ensaios realizados sugeriram a necessidade de se transformar a experimentação em experienciação, de roteiro semi-estruturado. Esta mudança poderia levar os estudantes a construir/compreender o conceito basilar de energia, os processos de transferência e as perdas de energia ocorridas durante os ensaios, tomando por base os princípios termoquímicos e termodinâmicos e estudando-os de modo integrado. Realizando atividades no contra-período com os alunos, logo se percebeu a dificuldade destes em entender certos aspectos do procedimento semi-estruturado, o que nos levou a iniciar o processo de experienciação com uma aula teórica sobre máquinas térmicas e outros aspectos relevantes da História das Ciências. Visando determinar se o processo de experienciação e a aula ministrada exerciam alguma influência sobre o processo de ensino/aprendizagem, dividiu-se uma classe em três grupos: o primeiro grupo (G1) ¿ de controle ¿ não participou da experienciação nem da aula, respondendo à questão relativa ao assunto na avaliação bimestral dissertativa obrigatória a partir de saberes obtidos durante as aulas regulares; o segundo grupo (G2) que, de todo o processo, apenas não participou da aula teórica e o terceiro grupo (G3) que cumpriu todas as etapas do processo. Constatou-se que a aula teórica e a mudança do tipo de roteiro propiciaram a ampliação dos elementos de cognição, constituindo-se, assim, em fatores facilitadores para a aprendizagem, o que pode ser sugerido pelo desempenho médio dos alunos de cada grupo / Abstract: Interdisciplinary experiments are an important tool for teaching / learning. Beginning with a structured script, we carried out a series of tests with Projectile Launcher Thermodynamic (LTP). The results of the tests suggested the need to turn the trial into experiencing, semi-structured script. This could lead students to build / understand the basic concept of energy transfer processes and energy losses occurring during the tests, based on thermochemical and thermodynamic principles and studying them in an integrated manner. Performing activities in counter-period with students soon realized the difficulty in understanding certain aspects of these semi-structured procedure, which led us to begin the process of experiencing with a lecture on heat engines and other relevant aspects of the history of Sciences. To determine whether the process of experiencing and classroom instruction exerted some influence on the process of teaching / learning, a class was divided into three groups: the first group (G1) - control - did not participate in class or experiencing, responding to matter relating to the subject in compulsory Essay bimonthly review from knowledge obtained during regular classes; the second group (G2) that the whole process, not only attended the lecture and the third group (G3) who fulfilled all stages of the process. It was noted that the theoretical class and change the type of script enabled the expansion of the elements of cognition, constituting thus on factors that facilitate learning, which may be suggested by the average performance of students in each group / Mestrado / Físico-Química / Mestre em Química

Face à la demande énergétique de plus en plus croissante, et les problèmes environnementaux qui en découlent, la biomasse, en tant que vecteur énergétique et en association avec des techniques thermochimiques de conversion en gaz combustibles, pourrait être un vecteur énergétique intéressant s’il est produit de manière durable. En effet, accroitre le bouquet énergétique, en substituant d’avantage les énergies fossiles par des énergies renouvelables est devenu une réalité incontournable. De ce fait, les résidus agro-sylvo-pastoraux présentent un potentiel important au Sénégal en général et en particulier dans la région de Ziguinchor jadis appelée grenier du Sénégal, et des technologies de valorisation comme la pyrolyse et gazéification se trouvent parmi les voies les plus prometteuses pour la production d’énergie. Ainsi le modèle dynamique de Saeman basé sur la détermination des propriétés intrinsèques des résidus utilisés a été mis en œuvre afin de simuler l’écoulement de la charge de coques de cajou, de palme et d’arachide. Le modèle dynamique ainsi développé va permettre d'étudier l’influence des conditions opératoires et propriétés rhéologiques sur les profils de chargement, qui conduiront par la suite aux meilleurs transferts de chaleur et de masse dans les fours tournants en situation inerte comme réactive. Les meilleures conditions expérimentales retenues pour cette étude hydrodynamique sont : des vitesses de rotations comprises entre 2 - 4 tr/min, une inclinaison de 1°, et un rapport longueur sur diamètre supérieur ou égal à 0,05. La gazéification des trois résidus sous différents atmosphères (100 % -H2O, 75 % -H2O / 25 %- CO2, 50 % -H2O / 50 % -CO2, 25 % -H2O / 75 % -CO2, et 100 % -CO2) et à différentes températures comprises entre 950 - 1050 °C dans un réacteur à lit fixe ont permis de valider les résultats issus de la littérature qui mettent bien en évidence l’effet positif de la température sur la cinétique de gazéification des différents chars de résidus de biomasse. La pyrolyse de nos trois échantillons donne ainsi des rendements qui sont de 36,44 % pour la coque d’arachide, 37,28 % pour la coque de cajou et 39,97 % pour la coque de palme et quant à leur gazéification, elle conduit respectivement à des énergies d’activation comprises entre 110 - 126 kJ/mol, 104 - 125 kJ/mol et 116 - 150 kJ/mol. Les mesures expérimentales montrent aussi l’influence de la température sur la valeur du PCI des gaz obtenus (8 - 12 MJ/Nm3) et que ce PCI des gaz est inversement proportionnel à la taille des particules de biomasse. Par ailleurs la gazéification sous atmosphère mixte de vapeur d’eau et de gaz carbonique a montré que la réactivité des différents chars est fonction de l’augmentation de la concentration en vapeur d’eau. Le bilan global d’une telle étude expérimentale sur l’hydrodynamique et sur la dégradation thermique visant la maîtrise des phénomènes au sein des fours tournants permet ainsi une première analyse dans la mise en place de combustibles alternatifs pour la valorisation des potentialités locales de la région verte de la Casamance. / In view of the growing energy demand and the resulting environmental problems, biomass as an energy vector and at combination with thermochemical techniques for conversion into combustible gases, could be an interesting energy vector if it is produced in a sustainable manner. Indeed, increasing the energy mix, by replacing fossil fuels with renewable energies, has become an undeniable reality. As a result, agro-sylvo-pastoral residues have significant potential in Senegal in general and in particular in Ziguinchor region, formerly known as Senegal's granary, and valorisation technologies such as pyrolysis and gasification are among the most promising way for energy production. The Seaman’s dynamic model based on the determination of the intrinsic properties of the residues used has been implemented in order to simulate the flow of cashew, palm and peanut shells. Thus, the dynamic model developed will make it possible to study the influence of the operating conditions and rheological properties on the loading profiles which will conduct later of the best heat and mass transfers in the rotating furnaces in inert and reactive conditions. The best experimental conditions for this hydrodynamic study are: rotational speeds between 2 - 4 rpm, inclination of 1 °, and length to diameter ratio greater than or equal to 0.05. The gasification of the three residues under different atmospheres (100 % -H2O, 75 % -H2O / 25 %-CO2, 50 % -H2O / 50 % -CO2, 25 % -H2O / 75 % -CO2, and 100 % -CO2) and at different temperatures between 950 - 1050 °C in a fixed bed reactor enable to validate the results from the literature which clearly show the positive effect of temperature on the gasification kinetics of the various chars. The pyrolysis of our three samples gives yields of 36.44 % for the peanut shell, 37.28 % for the cashew shell and 39.97 % for the palm shell; and when gasified, it leads respectively at activation energies between 110 - 126 kJ / mol, 104 - 125 kJ / mol and 116 - 150 kJ / mol. The experimental measurements also show the influence of temperature on the Lower heating gas values (LHV) obtained (8 - 12 MJ/Nm3) and that, this LHV of gas is inversely proportional to the size of the biomass particles. Moreover, the gasification under mixed atmosphere of steam and carbon dioxide showed that the reactivity of the different chars depend on the increase of the concentration of water vapor. The overall assessment of such an experimental study on the hydrodynamic and thermal degradation of our residues aimed at controlling the phenomena within rotating furnaces (kilns) allows an initial analysis in the setting up of alternative fuels for the valorization of the local potentialities of the green region of Casamance.

The chemical evolution with respect to time of complex macroscopic mixtures such as interstellar clouds and Titan’s atmosphere is governed via a mutual competition between thousands of simultaneous processes, including thousands of chemical reactions. Chemical kinetic modeling, which attempts to understand their macroscopic observables as well as their overall reaction mechanism through a detailed understanding of their microscopic reactions and processes, thus require thousands of rate coefficients and product distributions. At present, however, just a small fraction of these have been well-studied and measured; in addition, at the relevant low temperatures, such information becomes even more scarce. Due to the recent developments in both theoretical kinetics as well as in ab initio electronic structure calculations, it is now possible to predict accurate reaction rate coefficients and product distributions from first-principles at various temperatures, often in less time, than through the running of an experiment. Here, the results of a first principles theoretical investigation into both the reaction rate coefficients as well as the final product distributions for the reactions between the ground state CH radical (X2Π) and various C1-C3 hydrocarbons is presented; together, these constitute a set of reactions important to modeling efforts relevant to mixtures such as interstellar clouds and Titan’s atmosphere.

Orientador: Pedro Oliver Dunstan Lozano / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-22T07:28:40Z (GMT). No. of bitstreams: 1 Khan_AbdulMajeed_D.pdf: 3004508 bytes, checksum: 1d8c778094bf0cb1b93fa7bf80e19074 (MD5) Previous issue date: 2013 / Resumo: Os adutos MX2.nL (M = Mn, Fe, Co, Ni, Cu ou Zn, L = 3-cianopiridina, piperidina ou piperazaina, X = Br, n = 0,5, 0,75, 1, 1,5, 2 ou 4), foram sintetizados e caracterizados através de análise elementar, determinação de pontos de fusão, espectroscopia IV e eletrônica e análise termogravimétrica. Todos os adutos são sólidos e sensíveis à umidade atmosférica. Os dados espectroscópicos na região do infravermelho, para os adutos, indicam a presença de um mesmo padrão de bandas em comparação com os respectivos ligantes livres. No entanto, deslocamentos de algumas bandas são evidentes devido à coordenação dos íons metálicos aos ligantes. As entalpias de dissolução em HCl 1,2 molL dos adutos, brometos metálicos e ligantes, foram determinados. Através de ciclos termoquímicos apropriados, foram calculadas as variações de entalpia padrão para as reações: MBr2 (s) + nL (s,l) MBr2.nL (s) DrH MBr2.nL (s) MBr2 (s) + nL (g) DDH MBr2 (g) + nL (g) MBr2.nL (s) DMH Foram também calculadas as variações entálpicas padrão de formação dos adutos e as variações entálpicas padrão da ligação metal-nitrogênio. Os parâmetros termoquímicos permitiram determinar a ordem de acidez dos adutos: para os adutos de ligante 3-cianopiridina: NiBr2>FeBr2> CoBr2>MnBr2 e ZnBr2>CuBr2, para os adutos de ligante piperidina: FeBr2 > MnBr2, CoBr2 > NiBr2, para adutos de ligante piperazina: FeBr2 > MnBr2 > NiBr2 e CuBr2 > ZnBr2 > CoBr2. A ordem de basicidade das ligantes e (Piperidina) >(3-cianopiridina) para os adutos de ZnBr2 e (Piperidina) > (Piperazina) para os adutos de CuBr2. / Abstract: The adducts MX2.nL (M = Mn, Fe, Co, Ni, Cu or Zn, L = 3-cyanopyridine, piperidine or piperazaina, X = Br, n = 0.5, 0.75, 1, 1.5, 2 or 4), were synthesized and characterized by elemental analysis, melting point measurements of the adducts, vibrational and electronic spectroscopy and thermogravimetric analysis. All adducts are solid and sensitive to moisture. The spectroscopic data in the infrared region, indicate the presence of a similar band pattern as compared with the free ligands. However, dislocation of some bands are observed due to coordination of the metal ions to the ligands. The enthalpies of dissolution in HCl 1.2 molL of the adducts, metal bromides and ligands have been determined. Through appropriate thermochemical cycles, we calculated the standard enthalpy changes for the reactions: MBr2 (s) + nL (s,l) MBr2.nL (s) DrH MBr2.nL (s) MBr2 (s) + nL (g) DDH MBr2 (g) + nL (g) MBr2.nL (s) DMH Standard enthalpy of formation and standard mean enthalpy of Metal-Nitrogen bonds were also calculated. The thermochemical parameters allowed to determine the acidity order of metal bromides for the adducts of the same stoichiometry: For the adducts of ligand 3-cyanopyridine: NiBr2> FeBr2> CoBr2> MnBr2 and ZnBr2> CuBr2. for the adducts of ligand piperidine: FeBr2> MnBr2 and CoBr2> NiBr2. for the adducts of ligand piperazine: FeBr2> MnBr2> NiBr2 and CuBr2> ZnBr2> CoBr2. The order of basicity is (Piperidine)> (3-cyanopyridine) for the adducts of ZnBr2 and (Piperidine)> (Piperazine) for the adducts of CuBr2. / Doutorado / Quimica Inorganica / Doutor em Ciências

The purpose of this dissertation is to investigate the thermochemical properties of nonelectrolyte solutes dissolved in ternary solvent mixtures, and to develop mathematical expressions for predicting and describing behavior in the solvent mixtures. Forty-five ternary solvent systems were studied containing an ether (Methyl tert-butyl ether, Dibutyl ether, or 1,4-Dioxane), an alcohol (1-Propanol, 2-Propanol, 1-Butanol, 2-Butanol, or 2-Methyl-1-propanol), and an alkane (Cyclohexane, Heptane, or 2,2,4-Trimethylpentane) cosolvents. The Combined NIBS (Nearly Ideal Binary Solvent)/Redlich-Kister equation was used to assess the experimental data. The average percent deviation between predicted and observed values was less than ± 2 per cent error, documenting that this model provides a fairly accurate description of the observed solubility behavior. In addition, Mobile Order theory, the Kretschmer-Wiebe model, and the Mecke-Kempter model were extended to ternary solvent mixtures containing an alcohol (or an alkoxyalcohol) and alkane cosolvents. Expressions derived from Mobile Order theory predicted the experimental mole fraction solubility of anthracene in ternary alcohol + alkane + alkane mixtures to within ± 5.8%, in ternary alcohol + alcohol + alkane mixtures to within ± 4.0%, and in ternary alcohol + alcohol + alcohol mixtures to within ± 3.6%. In comparison, expressions derived from the Kretschmer-Wiebe model and the Mecke-Kempter model predicted the anthracene solubility in ternary alcohol + alkane + alkane mixtures to within ± 8.2% and ± 8.8%, respectively. The Kretschmer-Wiebe model and the Mecke-Kempter model could not be extended easily to systems containing two or more alcohol cosolvents.

No description available.

Thermochemical water splitting cycles have been conceptualized and researched for over half a century, yet to this day none are commercially viable. The heavily studied Sulfur-Iodine cycle has been stalled in the early development stage due to a difficult HI-H₂O separation step and material compatibility issues. In an effort to avoid the azeotropic HI-H₂O mixture, an imidazolium-based ionic liquid was used as a reaction medium instead of water. Ionic liquids were selected based on their high solubility for SO₂, I₂, and tunable miscibility with water. The initial low temperature step of the Sulfur-Iodine cycle was successfully carried out in ionic liquid reaction medium. Kinetics of the reaction were investigated by I₂ colorimetry. The reaction also evolved H₂S gas, which led to the conceptual idea of a new Sulfur-Sulfur thermochemical cycle, shown below: / 4I₂(l)+4SO₂(l)+8H₂O(l)↔4H₂SO₄(l)+ 8HI(l) / 8HI(l)+H₂SO₄(l)↔ H₂S(g)+4H₂O(l)+4I₂(l) / 3H₂SO₄(g)↔ 3H₂O(g)+3SO₂(g)+1½O₂(g) / H₂S(g)+2H₂O(g)↔ SO₂(g)+3H₂(g) / The critical step in the Sulfur-Sulfur cycle is the steam reformation of H₂S. This highly endothermic step is shown to successfully occur at temperatures in excess of 800˚C in the presence of a molybdenum catalyst. A parametric study varying the H₂O:H₂S ratio, temperature, and residence time in a simple tubular quartz reactor was carried out and Arrhenius parameters were estimated. All reactive steps of the Sulfur-Sulfur cycle have been either demonstrated previously or demonstrated in this work. A theoretical heat-to-hydrogen thermal efficiency is estimated to be 55% at a hot temperature of 1100 K and 59% at 2000 K. As a highly efficient, all-fluid based thermochemical cycle, the Sulfur-Sulfur cycle has great potential for feasible process implementation for the transformation of high quality heat to chemical energy. / Graduation date: 2012

The hydrogen economy is a possible component of an energy future based on use of alternative and renewable energy sources, deemed desirable from the general consensus of the worldwide community that we do not want to further exacerbate the climate problems that we have introduced over the last two centuries from burning fossil fuels. The burning of fossil fuels emits toxic pollutants into the air, such as sulfur compounds and oxidized forms of nitrogen (NOx) but also emit copious amounts of the inert carbon dioxide. The latter is widely recognized as the major cause of the global warming phenomenon. For a hydrogen economy to develop, efficient means of hydrogen generation are required. Thermochemical cycles were conceived in the 1960s but only one operating pilot plant and no commercial installations based on the processes have been built. In the present work the use of a membrane reactor to enable the newly conceived Sulfur-Sulfur cycle, based on equations 1 - 3 is modeled. / 4H₂O+4SO₂ -> H₂S + 3H₂SO₄ Eq. 1 / H₂SO₄ -> SO₂ + H₂O + 1/2O₂ Eq. 2 / H₂S + 2H₂O -> SO₂ + 3H₂ Eq. 3 / The rationale for the use of a membrane reactor to enable the cycle is based on enhancing extent of reaction beyond its predicted equilibrium point due to the severely unfavorable thermochemical parameters for the steam reforming of hydrogen sulfide reaction (Eq. 3 above) which has a low equilibrium concentration of products. The membrane reactor will employ a molybdenum sulfide catalyst driving the steam reformation of hydrogen sulfide reaction and simultaneous extraction of hydrogen (one of the products) will allowing for the reaction to occur to higher extent. A computational model of a catalytic membrane reactor was constructed using the well-known finite element model package Comsol v4.1 in which a catalytic microchannel reactor separated from a sweep gas by a thin hydrogen permeable membrane is built and parametric sweeps to evaluate the effect of membrane transport parameters, pressure and gas feed velocities are calculated. Though the steam reforming of hydrogen sulfide reaction has a competing thermal cracking reaction, the present work focuses on modeling one reaction only (the steam reformation reaction) for simplicity. Fully dense metallic membranes with chemselective permeability to hydrogen are modeled with transport parameters derived from reported literature values for similar applications. The results show that employing a membrane reactor does significantly affect the completeness of the reaction by product extraction (if you do run the model with membrane transport set to zero, compare the extent at zero with extent at 3.6x10⁻⁶ mol.s⁻¹.m⁻²). The effect of changing sweep gas velocity is contingent on membrane properties, and membranes with small diffusion coefficients severely limit the ability of extraction of hydrogen from the feed. Therefore, it is more important that membranes with very high hydrogen permeability be employed in designing a reactor to implement this process, allowing for effective hydrogen separation and high conversion of the reactants in the process. Reactor pressure has minimal effect on the extent of reaction and therefore reactors designed to implement the process may be designed to operate at close to ambient pressure. / Graduation date: 2012

In this work, the Drift Tube Ion Mobility technique is used to study the hydrophobic hydration and solvation of organic ions and measure the thermochemistry and kinetics of ion-molecule reactions. Furthermore, an exploratory study of the intracluster polymerization of isoprene will be presented and discussed. The ion hydration study is focused on the C3H3+ cation1 and Pyridine▪+ radical cation.2 The chemistry of the cyclic C3H3+ cation1 has received considerable attention and continues to be an active area of research.3-7 The binding energies of the first 5 H2O molecules to c-C3H3+ were determined by equilibrium measurements. The measured binding energies of the hydrated clusters of 9-12 kcal/mol are typical of carbon-based CH+•••X hydrogen bonds. The ion solvation with the more polar CH3CN molecules results in stronger bonds consistent with the increased ion-dipole interaction. Ab initio calculations show that the lowest energy isomer of the c-C3H3+(H2O)4 cluster consists of a cyclic water tetramer interacting with the c-C3H3+ ion, which suggests the presence of orientational restraint of the water molecules consistent with the observed large entropy loss. The c-C3H3+ ion is deprotonated by 3 or more H2O molecules, driven energetically by the association of the solvent molecules to form strongly hydrogen bonded (H2O)nH+ clusters. The kinetics of the associative proton transfer (APT) reaction C3H3+ + nH2O → (H2O)nH+ + C3H2• exhibits an unusually steep negative temperature coefficient of k = cT(sup>63±4 (or activation energy of -32 ± 1 kcal mol-1). The behavior of the C3H3+/water system is exactly analogous to the benzene+• /water system8,9, suggesting that the mechanism, kinetics and large negative temperature coefficients may be general to multibody APT reactions. These reactions can become fast at low temperatures, allowing ionized polycyclic aromatics to initiate ice formation in cold astrochemical environments.The solvation energies of the pyridine•+ radical cation by 1- 4 H2O molecules are determined by equilibrium measurements in the drift cell. The binding energies of the pyridine•+(H2O)n clusters are similar to the binding energies of protonated pyridineH+(H2O)n clusters that involve NH+∙∙OH2 bonds, and different from those of the solvated radical benzene•+(H2O)n ions that involve CHδ+∙∙OH2 bonds. These relations indicate that the observed pyridine•+ ions have the distonic •C5H4NH+ structure that can form NH+∙∙OH2 bonds. The observed thermochemistry and ab initio calculations show that these bonds are not affected significantly by an unpaired electron at another site of the ion. The distonic structure is also consistent with the reactivity of pyridine•+ in H atom transfer, intra-cluster proton transfer and deprotonation reactions. The results present the first measured stepwise solvation energies of distonic ions, and demonstrate that cluster thermochemistry can identify distonic structures.The gas phase clustering of small molecules around the hydronium ion is of fundamental interest and is relevant to important atmospheric and astrophysical processes. In this work, the equilibrium constants for the formation of the H3O+(X)n clusters with X = H2, N2 and CO and n = 1-3 at different temperatures are measured using the drift tube technique10. The arrival time distributions (ATDs) of the injected H3O+ and the H3O+(X)n clusters formed inside the cell are measured under equilibrium conditions. The resulting binding energies for the addition of one and two hydrogen molecules are similar [3.4 and 3.5 kcal/mol, respectively). For the N2 clustering with n = 1-3, the measured binding energies are 7.9, 6.9 and 5.4 kcal/mol, respectively. The clustering of CO on the H3O+ ion exhibits a relatively strong binding energy (11.5 kcal/mol) consistent with the dipole moment and polarizability of the CO molecule. Theoretical calculations of the lowest energy structures are correlated to the experimental results. Finally, intracluster polymerization leading to the formation of covalent bonded oligomer ions has been investigated following the ionization of neutral isoprene clusters. The results indicate that isoprene dimer cation has a structure similar to that of the limonene radical cation. Mass-selected mobility and dissociation studies also indicate that the larger isoprene cluster ions have covalent bonded structures. The conversion of molecular clusters into size-selected oligomers is an important process not only for detailed understanding of the early stages of polymerization but also for practical applications such as the formation of new polymeric materials with controlled and unusual properties.