Relevant bibliographies by topics / Thermochemistry - Molecules

Academic literature on the topic 'Thermochemistry - Molecules'

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Published: 7 September 2023

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Journal articles on the topic "Thermochemistry - Molecules"

1

Gu, Geun Ho, Petr Plechac, and Dionisios G. Vlachos. "Thermochemistry of gas-phase and surface species via LASSO-assisted subgraph selection." Reaction Chemistry & Engineering 3, no. 4 (2018): 454–66. http://dx.doi.org/10.1039/c7re00210f.

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RAGHAVACHARI, KRISHNAN, BORIS STEFANOV, and LARRY CURTISS. "Accurate density functional thermochemistry for larger molecules." Molecular Physics 91, no. 3 (June 20, 1997): 555–59. http://dx.doi.org/10.1080/00268979709482745.

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RAGHAVACHARI, By KRISHNAN, BORIS B. STEFANOV, and LARRY A. CURTISS. "Accurate density functional thermochemistry for larger molecules." Molecular Physics 91, no. 3 (June 1997): 555–60. http://dx.doi.org/10.1080/002689797171445.

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4

Haworth, Naomi L., Michael B. Sullivan, Angela K. Wilson, Jan M. L. Martin, and Leo Radom. "Structures and Thermochemistry of Calcium-Containing Molecules." Journal of Physical Chemistry A 109, no. 40 (October 2005): 9156–68. http://dx.doi.org/10.1021/jp052889h.

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Bouchoux, Guy, Danielle Leblanc, William Bertrand, Terance B. McMahon, Jan E. Szulejko, Florence Berruyer-Penaud, Otilia Mó, and Manuel Yáñez. "Protonation Thermochemistry of Selected Hydroxy- and Methoxycarbonyl Molecules." Journal of Physical Chemistry A 109, no. 51 (December 2005): 11851–59. http://dx.doi.org/10.1021/jp054955l.

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Griller, David, J. A. Martinho Simoes, P. Mulder, B. A. Sim, and D. D. M. Wayner. "Unifying the solution thermochemistry of molecules, radicals, and ions." Journal of the American Chemical Society 111, no. 20 (September 1989): 7872–76. http://dx.doi.org/10.1021/ja00202a031.

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7

Bross, David H., and Kirk A. Peterson. "Composite thermochemistry of gas phase U(VI)-containing molecules." Journal of Chemical Physics 141, no. 24 (December 28, 2014): 244308. http://dx.doi.org/10.1063/1.4904721.

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8

Nagy, Balázs, Péter Szakács, József Csontos, Zoltán Rolik, Gyula Tasi, and Mihály Kállay. "High-Accuracy Theoretical Thermochemistry of Atmospherically Important Sulfur-Containing Molecules." Journal of Physical Chemistry A 115, no. 26 (July 7, 2011): 7823–33. http://dx.doi.org/10.1021/jp203406d.

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9

Barreto, Patr�cia R. P., Alessandra F. A. Vilela, and Ricardo Gargano. "Thermochemistry of molecules in the B/F/H/N system." International Journal of Quantum Chemistry 103, no. 5 (2005): 659–84. http://dx.doi.org/10.1002/qua.20566.

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10

Karton, Amir. "A computational chemist's guide to accurate thermochemistry for organic molecules." Wiley Interdisciplinary Reviews: Computational Molecular Science 6, no. 3 (February 15, 2016): 292–310. http://dx.doi.org/10.1002/wcms.1249.

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Dissertations / Theses on the topic "Thermochemistry - Molecules"

1

Lee, Matthew Colin John. "Correlations between MO Eigenvectors and the Thermochemistry of Simple Organic Molecules, Related to Empirical Bond Additivity Schemes." The University of Waikato, 2008. http://hdl.handle.net/10289/2623.

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A bondingness term is further developed to aid in heat of formation (ΔfHº) calculations for C, N, O and S containing molecules. Bondingness originated from qualitative investigations into the antibonding effect in the occupied MOs of ethane. Previous work used a single parameter for bondingness to calculate ΔfHº in an alkane homologous series using an additivity scheme. This work modifies the bondingness algorithm and uses the term to parameterise a test group of 345 molecules consisting of 17 subgroups that include alkanes, alkenes, alkynes, alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, amines, amides, diazenes, nitriles, nitroalkanes, nitrates, thiols and benzenoids. Comparing experimental with calculated ΔfHº values, a standard deviation for the residuals of 6.3 kJ mol 1 can be achieved using bondingness with a simple steric repulsion term (SSR) in a bond additivity scheme, and a standard deviation of 5.2 kJ mol 1 can be achieved using a Lennard-Jones potential. The method is compared with the group method of Pedley, which for a slightly smaller set of 338 molecules, a subset of the test set of 345 molecules, gives a standard deviation of 7.0 kJ mol 1. Bondingness, along with SSR or a Lennard-Jones potential, is parameterised in the lowest level of ab initio (HF-SCF) or semiempirical quantum chemical calculations. It therefore may be useful in determining the ΔfHº values for the largest molecules that are amenable to quantum chemical calculation. As part of our analysis we calculated the difference between the lowest energy conformer and the average energy of a mixture populated with higher energy conformers. This is the difference between the experimental ΔfHº value and the ΔfHº calculated for a single conformer. Example calculations which we have followed are given by Dale and Eliel et al.. Dale calculates the energy difference for molecules as large as hexane using relative energies based on the number of 1,4 gauche interactions. We have updated these values with constant increments ascertained by Klauda et al. as well as ab initio MP2 cc-pVDZ relative energies and have included calculations for heptane and octane.
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2

Platt, Sean P. "Interactions of the Naphthalene Radical Cation with Polar and Unsaturated Molecules in the Gas Phase." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4210.

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Characterizing the interactions of solvent molecules with ions is fundamental in understanding the thermodynamics of solution chemistry. These interactions are difficult to observe directly in solution because the number of solvent molecules far exceed that of ions. This lend the gas phase to be the ideal medium in the study ion-solvent interactions on a molecular level. Ionized polycyclic aromatic hydrocarbon (PAH) molecules can readily form hydrogen bonds with neutral solvent molecules in aqueous and interstellar medium. Previous research has been done for stepwise solvation of small molecules such as benzene+, pyridine, and phenylacetylene. The similarity in these results show that these organic ions can be considered prototypical model systems for aromatic ion-neutral solvent interactions. The goal of this dissertation is to demonstrate that naphthalene can act as a prototypical model of PAH ions for ion-solvent interactions. Two types of experiments are considered throughout this dissertation using ion mobility mass spectrometry: (1) ion-neutral equilibrium thermochemistry and (2) mobility measurements. For thermochemistry experiments, the naphthalene radical cation was injected into the drift cell containing helium and/or neutral solvent vapor and the enthalpy and entropy changes were measured by varying the drift cell temperature and measuring the equilibrium constants. The results of these studies showed that small polar molecules bind to naphthalene with similar energy based on the measured by the enthalpy changes. Unsaturated aliphatic molecules behave similarly, but with much lower binding energy. Aromatic ions tend to bind to the naphthalene with lower binding energy than that observed with the benzene ion. The results for small polar molecules were compared to similar studies using the phenyl cation. The second series of experiments required the coexpansion of the naphthalene and benzene or pyridine. Injecting theses dimers into the drift cell allowed the measurement of reduced mobility on the dimers at a series of temperatures. These were used to calculate the average collision cross section and thus give insight in to the structure of these aromatic dimers. Structures were determined by comparing these results to those predicted by DFT calculations.
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Pearcy, Adam C. "Non-covalent and covalent interactions between phenylacetylene and quinoline radical cations with polar and non-polar molecules in the gas phase." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5990.

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Gas phase molecular clusters present an ideal medium for observing factors that drive chemical reactions without outside interferences from excessive solvent molecules. Introducing an ion into the cluster promotes ion-molecule interactions that may manifest in a variety of non-covalent or even covalent binding motifs and are of significant importance in many fields including atmospheric and astronomical sciences. For instance, in outer space, molecules are subject to ionizing radiation where ion-molecule reactions become increasingly competitive to molecule-molecule interactions. To elucidate individual ion-molecule interaction information, mass spectrometry was used in conjunction with appropriate theoretical calculations. Three main categories of experiment were conducted in this dissertation. The first of which were thermochemical equilibrium measurements where an ion was introduced to an ion mobility drift cell wherein thermalizing collisions occur with helium buffer gas facilitating a reversible reaction with a neutral molecule allowing the standard changes in enthalpy and entropy to be determined. The second type of experiment was an ion mobility experiment where an ionized homo- or hetero-cluster was injected into the drift cell at specific conditions allowing the reduced mobility and collisional cross-section to be evaluated. Thirdly, kinetics measurements were taken following injection of an ion into the drift cell were an irreversible reaction ensued with the neutral species hindering equilibrium, but prompting rate constant assessment. Previous research has laid the groundwork for this dissertation as the results and discussion contained herein will build upon existing data while maintaining originality. For example, past work has given support for ion-molecule reactions involving precursor species such as acetylene and hydrogen cyanide to form more complex organics, perhaps leading to biologically relevant species. The chemical systems studied for this research are either ionized substituted benzenes like phenylacetylene and benzonitrile or polycyclic aromatic nitrogen-containing hydrocarbons like quinoline and quinoxaline interacting with a variety of neutral species. Hydrogen bonding and its many sub-sections are of the utmost importance to the kinds of reactions studied here. Past work has shown the tendency of organic radical cations to form conventional and unconventional ionic hydrogen bonds with gas phase solvents. Other non-covalent modes of interaction have also been detected in addition to the formation of covalently bound species. Gas phase reactions studied here will explore, via mass-selected ion mobility, reversible and irreversible reactions leading to binding enthalpy and entropy and rate constant determination, respectively, in addition to collisional cross-section determination.
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4

Dearden, David Vernell Beauchamp Jesse L. Beauchamp Jesse L. "Experimental probes of gas phase ions and molecules : I. Product kinetic energy release measurements as a probe of reaction thermochemistry, dynamics, and chemical structure in systems containing transition metal ions. II. Photoelectron and optical studies of organic transient species /." Diss., Pasadena, Calif. : California Institute of Technology, 1989. http://resolver.caltech.edu/CaltechETD:etd-02082007-130036.

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5

Haworth, Naomi Louise. "Quantum Chemical Studies of Thermochemistry, Kinetics and Molecular Structure." Thesis, The University of Sydney, 2003. http://hdl.handle.net/2123/509.

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This thesis is concerned with a range of chemical problems which are amenable to theoretical investigation via the application of current methods of computational quantum chemistry. These problems include the calculation of accurate thermochemical data, the prediction of reaction kinetics, the study of molecular potential energy surfaces, and the investigation of molecular structures and binding. The heats of formation (from both atomisation energies and isodesmic schemes) of a set of approximately 120 C1 and C2 fluorocarbons and oxidised fluorocarbons (along with C3F6 and CF3CHFCF2) were calculated with the Gaussian-3 (G3) method (along with several approximations thereto). These molecules are of importance in the flame chemistry of 2-H-heptafluoropropane, which has been proposed as a potential fire retardant with which to replace chloro- and bromofluorocarbons (CFC�s and BFC�s). The calculation of the data reported here was carried out in parallel with the modelling studies of Hynes et al.1-3 of shock tube experiments on CF3CHFCF3 and on C3F6 with either hydrogen or oxygen atoms. G3 calculations were also employed in conjunction with the experimental work of Owens et al.4 to describe the pyrolysis of CFClBr2 (giving CFCl) at a radiation wavelength of 265 nm. The theoretical prediction of the dissociation energy of the two C-Br bonds was found to be consistent with the energy at which carbene production was first observed, thus supporting the hypothesis that the pyrolysis releases two bromine radicals (rather than a Br2 molecule). On the basis of this interpretation of the experiments, the heat of formation of CFClBr2 is predicted to be 184 � 5 kJ mol-1, in good agreement with the G3 value of 188 � 5 kJ mol-1. Accurate thermochemical data was computed for 18 small phosphorus containing molecules (P2, P4, PH, PH2, PH3, P2H2, P2H4, PO, PO2, PO3, P2O, P2O2, HPO, HPOH, H2POH, H3PO, HOPO and HOPO2), most of which are important in the reaction model introduced by Twarowski5 for the combustion of H2 and O2 in the presence of phosphine. Twarowski reported that the H + OH recombination reaction is catalysed by the combustion products of PH3 and proposed two catalytic cycles, involving PO2, HOPO and HOPO2, to explain this observation. Using our thermochemical data we computed the rate coefficients of the most important reactions in these cycles (using transition state and RRKM theories) and confirmed that at 2000K both cycles have comparable rates and are significantly faster than the uncatalysed H + OH recombination. The heats of formation used in this work on phosphorus compounds were calculated using the G2, G3, G3X and G3X2 methods along with the far more extensive CCSD(T)/CBS type scheme. The latter is based on the evaluation of coupled cluster energies using the correlation consistent triple-, quadruple- and pentuple-zeta basis sets and extrapolation to the complete basis set (CBS) limit along with core-valence correlation corrections (with counterpoise corrections for phosphorus atoms), scalar relativistic corrections and spin-orbit coupling effects. The CCSD(T)/CBS results are consistent with the available experimental data and therefore constitute a convenient set of benchmark values with which to compare the more approximate Gaussian-n results. The G2 and G3 methods were found to be of comparable accuracy, however both schemes consistently underestimated the benchmark atomisation energies. The performance of G3X is significantly better, having a mean absolute deviation (MAD) from the CBS results of 1.8 kcal mol-1, although the predicted atomisation energies are still consistently too low. G3X2 (including counterpoise corrections to the core-valence correlation energy for phosphorus) was found to give a slight improvement over G3X, resulting in a MAD of 1.5 kcal mol-1. Several molecules were also identified for which the approximations underlying the Gaussian-n methodologies appear to be unreliable; these include molecules with multiple or strained P-P bonds. The potential energy surface of the NNH + O system was investigated using density functional theory (B3LYP/6-31G(2df,p)) with the aim of determining the importance of this route in the production of NO in combustion reactions. In addition to the standard reaction channels, namely decomposition into NO + NH, N2 + OH and H + N2O via the ONNH intermediate, several new reaction pathways were also investigated. These include the direct abstraction of H by O and three product channels via the intermediate ONHN, giving N2 + OH, H + N2O and HNO + N. For each of the species corresponding to stationary points on the B3LYP surface, valence correlated CCSD(T) calculations were performed with the aug-cc-pVxZ (x = Q, 5) basis sets and the results extrapolated to the complete basis set limit. Core-valence correlation corrections, scalar relativistic corrections and spin orbit effects were also included in the resulting energetics and the subsequent calculation of thermochemical data. Heats of formation were also calculated using the G3X method. Variational transition state theory was used to determine the critical points for the barrierless reactions and the resulting B3LYP energetics were scaled to be compatible with the G3X and CCSD(T)/CBS values. As the results of modelling studies are critically dependent on the heat of formation of NNH, more extensive CCSD(T)/CBS calculations were performed for this molecule, predicting the heat of formation to be 60.6 � 0.5 kcal mol-1. Rate coefficients for the overall reaction processes were obtained by the application of multi-well RRKM theory. The thermochemical and kinetic results thus obtained were subsequently used in conjunction with the GRIMech 3.0 reaction data set in modelling studies of combustion systems, including methane / air and CO / H2 / air mixtures in completely stirred reactors. This study revealed that, contrary to common belief, the NNH + O channel is a relatively minor route for the production of NO. The structure of the inhibitor Nd-(N'-Sulfodiaminophosphinyl)-L-ornithine, PSOrn, and the nature of its binding to the OTCase enzyme was investigated using density functional (B3LYP) theory. The B3LYP/6-31G(d) calculations on the model compound, PSO, revealed that, while this molecule could be expected to exist in an amino form in the gas phase, on complexation in the active site of the enzyme it would be expected to lose two protons to form a dinegative imino tautomer. This species is shown to bind strongly to two H3CNHC(NH2)2+ moieties (model compounds for arginine residues), indicating that the strong binding observed between inhibitor and enzyme is partially due to electrostatic interactions as well as extensive hydrogen bonding (both model Arg+ residues form hydrogen bonds to two different sites on PSO). Population analysis and hydrogen bonding studies have revealed that the intramolecular bonding in this species consists of either single or semipolar bonds (that is, S and P are not hypervalent) and that terminal oxygens (which, being involved in semipolar bonds, carry negative charges) can be expected to form up to 4 hydrogen bonds with residues in the active site. In the course of this work several new G3 type methods were proposed, including G3MP4(SDQ) and G3[MP2(Full)], which are less expensive approximations to G3, and G3X2, which is an extension of G3X designed to incorporate additional electron correlation. As noted earlier, G3X2 shows a small improvement on G3X; G3MP4(SDQ) and G3[MP2(Full)], in turn, show good agreement with G3 results, with MAD�s of ~ 0.4 and ~ 0.5 kcal mol-1 respectively. 1. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 5967. 2. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 54. 3. R. G. Hynes, J. C. Mackie and A. R. Masri, Proc. Combust. Inst., 2000, 28, 1557. 4. N. L. Owens, Honours Thesis, School of Chemistry, University of Sydney, 2001. 5. A. Twarowski, Combustion and Flame, 1995, 102, 41.
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6

Haworth, Naomi Louise. "Quantum Chemical Studies of Thermochemistry, Kinetics and Molecular Structure." University of Sydney. Chemistry, 2003. http://hdl.handle.net/2123/509.

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This thesis is concerned with a range of chemical problems which are amenable to theoretical investigation via the application of current methods of computational quantum chemistry. These problems include the calculation of accurate thermochemical data, the prediction of reaction kinetics, the study of molecular potential energy surfaces, and the investigation of molecular structures and binding. The heats of formation (from both atomisation energies and isodesmic schemes) of a set of approximately 120 C1 and C2 fluorocarbons and oxidised fluorocarbons (along with C3F6 and CF3CHFCF2) were calculated with the Gaussian-3 (G3) method (along with several approximations thereto). These molecules are of importance in the flame chemistry of 2-H-heptafluoropropane, which has been proposed as a potential fire retardant with which to replace chloro- and bromofluorocarbons (CFC�s and BFC�s). The calculation of the data reported here was carried out in parallel with the modelling studies of Hynes et al.1-3 of shock tube experiments on CF3CHFCF3 and on C3F6 with either hydrogen or oxygen atoms. G3 calculations were also employed in conjunction with the experimental work of Owens et al.4 to describe the pyrolysis of CFClBr2 (giving CFCl) at a radiation wavelength of 265 nm. The theoretical prediction of the dissociation energy of the two C-Br bonds was found to be consistent with the energy at which carbene production was first observed, thus supporting the hypothesis that the pyrolysis releases two bromine radicals (rather than a Br2 molecule). On the basis of this interpretation of the experiments, the heat of formation of CFClBr2 is predicted to be 184 � 5 kJ mol-1, in good agreement with the G3 value of 188 � 5 kJ mol-1. Accurate thermochemical data was computed for 18 small phosphorus containing molecules (P2, P4, PH, PH2, PH3, P2H2, P2H4, PO, PO2, PO3, P2O, P2O2, HPO, HPOH, H2POH, H3PO, HOPO and HOPO2), most of which are important in the reaction model introduced by Twarowski5 for the combustion of H2 and O2 in the presence of phosphine. Twarowski reported that the H + OH recombination reaction is catalysed by the combustion products of PH3 and proposed two catalytic cycles, involving PO2, HOPO and HOPO2, to explain this observation. Using our thermochemical data we computed the rate coefficients of the most important reactions in these cycles (using transition state and RRKM theories) and confirmed that at 2000K both cycles have comparable rates and are significantly faster than the uncatalysed H + OH recombination. The heats of formation used in this work on phosphorus compounds were calculated using the G2, G3, G3X and G3X2 methods along with the far more extensive CCSD(T)/CBS type scheme. The latter is based on the evaluation of coupled cluster energies using the correlation consistent triple-, quadruple- and pentuple-zeta basis sets and extrapolation to the complete basis set (CBS) limit along with core-valence correlation corrections (with counterpoise corrections for phosphorus atoms), scalar relativistic corrections and spin-orbit coupling effects. The CCSD(T)/CBS results are consistent with the available experimental data and therefore constitute a convenient set of benchmark values with which to compare the more approximate Gaussian-n results. The G2 and G3 methods were found to be of comparable accuracy, however both schemes consistently underestimated the benchmark atomisation energies. The performance of G3X is significantly better, having a mean absolute deviation (MAD) from the CBS results of 1.8 kcal mol-1, although the predicted atomisation energies are still consistently too low. G3X2 (including counterpoise corrections to the core-valence correlation energy for phosphorus) was found to give a slight improvement over G3X, resulting in a MAD of 1.5 kcal mol-1. Several molecules were also identified for which the approximations underlying the Gaussian-n methodologies appear to be unreliable; these include molecules with multiple or strained P-P bonds. The potential energy surface of the NNH + O system was investigated using density functional theory (B3LYP/6-31G(2df,p)) with the aim of determining the importance of this route in the production of NO in combustion reactions. In addition to the standard reaction channels, namely decomposition into NO + NH, N2 + OH and H + N2O via the ONNH intermediate, several new reaction pathways were also investigated. These include the direct abstraction of H by O and three product channels via the intermediate ONHN, giving N2 + OH, H + N2O and HNO + N. For each of the species corresponding to stationary points on the B3LYP surface, valence correlated CCSD(T) calculations were performed with the aug-cc-pVxZ (x = Q, 5) basis sets and the results extrapolated to the complete basis set limit. Core-valence correlation corrections, scalar relativistic corrections and spin orbit effects were also included in the resulting energetics and the subsequent calculation of thermochemical data. Heats of formation were also calculated using the G3X method. Variational transition state theory was used to determine the critical points for the barrierless reactions and the resulting B3LYP energetics were scaled to be compatible with the G3X and CCSD(T)/CBS values. As the results of modelling studies are critically dependent on the heat of formation of NNH, more extensive CCSD(T)/CBS calculations were performed for this molecule, predicting the heat of formation to be 60.6 � 0.5 kcal mol-1. Rate coefficients for the overall reaction processes were obtained by the application of multi-well RRKM theory. The thermochemical and kinetic results thus obtained were subsequently used in conjunction with the GRIMech 3.0 reaction data set in modelling studies of combustion systems, including methane / air and CO / H2 / air mixtures in completely stirred reactors. This study revealed that, contrary to common belief, the NNH + O channel is a relatively minor route for the production of NO. The structure of the inhibitor Nd-(N'-Sulfodiaminophosphinyl)-L-ornithine, PSOrn, and the nature of its binding to the OTCase enzyme was investigated using density functional (B3LYP) theory. The B3LYP/6-31G(d) calculations on the model compound, PSO, revealed that, while this molecule could be expected to exist in an amino form in the gas phase, on complexation in the active site of the enzyme it would be expected to lose two protons to form a dinegative imino tautomer. This species is shown to bind strongly to two H3CNHC(NH2)2+ moieties (model compounds for arginine residues), indicating that the strong binding observed between inhibitor and enzyme is partially due to electrostatic interactions as well as extensive hydrogen bonding (both model Arg+ residues form hydrogen bonds to two different sites on PSO). Population analysis and hydrogen bonding studies have revealed that the intramolecular bonding in this species consists of either single or semipolar bonds (that is, S and P are not hypervalent) and that terminal oxygens (which, being involved in semipolar bonds, carry negative charges) can be expected to form up to 4 hydrogen bonds with residues in the active site. In the course of this work several new G3 type methods were proposed, including G3MP4(SDQ) and G3[MP2(Full)], which are less expensive approximations to G3, and G3X2, which is an extension of G3X designed to incorporate additional electron correlation. As noted earlier, G3X2 shows a small improvement on G3X; G3MP4(SDQ) and G3[MP2(Full)], in turn, show good agreement with G3 results, with MAD�s of ~ 0.4 and ~ 0.5 kcal mol-1 respectively. 1. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 5967. 2. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 54. 3. R. G. Hynes, J. C. Mackie and A. R. Masri, Proc. Combust. Inst., 2000, 28, 1557. 4. N. L. Owens, Honours Thesis, School of Chemistry, University of Sydney, 2001. 5. A. Twarowski, Combustion and Flame, 1995, 102, 41.
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7

Belinassi, Antonio Ricardo. "Estudo da estrutura, ligação, termoquímica e espectroscopia dos sistemas SeI e 1[H, Se, I]." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-15122017-075556/.

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Novas espécies moleculares HSeI e HISe presentes na superfície de energia potencial (SEP) singleto 1[H, Se, I], como também a molécula diatômica monoiodeto de selênio (SeI), foram investigadas teoricamente em alto nível de teoria, CCSD(T)/CBS e SACASSCF/ MRCI, respectivamente, pela primeira vez na literatura. Todos estados eletrônicos dupletos e quartetos (Λ+S) que se correlacionam com os três primeiros canais de dissociação da molécula SeI, assim como os estados Ω associados, fornecem resultados conáveis para ajudar a entender a falta de dados experimentais de transições eletrônicas e no planejamento experimental para a determinação de parâmetros espectroscópicos. Ainda sobre este sistema, as probabilidades de transições foram calculadas para as transições X2 - X1, A1 - X1, A2 - X1, e A2 - X2, originadas pela transição proibida por spin 14Σ- X 2II, e os correspondentes tempos de vida radiativa obtidos. Os aspectos energéticos, estruturais e espectroscópicos associados aos estados estacion ários na SEP 1[H, Se, I] também foram caracterizados, assim como determinados os calores de formação dos isômeros. Os cálculos foram realizados com uma série de conjuntos de funções de base atômicas consistentes na correlação (aug-cc-pVnZ-PP, n = D, T, Q e 5) e os resultados extrapolados no limite de base completa (CBS). Contribuições de efeitos de correlação caroço-valência na função de onda e de anarmonicidade nas frequências vibracionais também foram explorados, fornecendo uma fonte de dados bastante confiáveis para estas espécies químicas ainda desconhecidas. O isômero HSeI é mais estável em relação ao HISe em 42; 04 kcal mol-1. Estes dois isômeros estão separados por uma barreira (ΔG#) de 52; 35 kcal mol-1. Correções devido aos efeitos de acoplamento spin- órbita e de relativísticos escalares também foram considerados na obtenção das energias de atomizações. Para o SeI, estimamos valores de calores de formação (ΔfH) de 36; 87 e 35; 16 kcal mol-1 a 0 K e a 298; 15 K; para o HSeI, obtivemos 18; 25 e 16; 72 kcal mol-1, respectivamente. De modo geral, esperamos que a conabilidade dos resultados presentes neste trabalho possa servir como um excelente guia para espectroscopistas na busca e caracterização dessas espécies químicas ainda desconhecidas experimentalmente.
New molecular species HSeI and HISe lying on the 1[H, Se, I] potencial energy surface (PES) as well as the diatomic molecule selenium monoiodide (SeI) were investigated theoretically for the rst time at a high level of theory, CCSD(T)/CBS and SACASSCF/MRCI, respectively. The overall picture of all doublet and quartet (Λ+S) states correlating with the three lowest dissociation channels of the SeI and the associated states provide reliable results to help understand the lack of experimental data on its transitions and to plan the investigation and determination of spectroscopic parameters. Transition probabilities were computed for the transitions X2 - X1, A1 - X1, A2 - X1, and A2 - X2, originated from the spin-forbidden 14Σ- - X 2II system, and the orresponding radiative lifetimes evaluated. The energetic, structural and spectroscopic aspects associated with the stationary points and transition state in the PES 1[H, Se, I] were also characterized, as well as the heat of formation of the isomers. Computations were carried out with the series correlation consistent basis sets (aug-cc-pVnZ-PP) and the results extrapolated to the complete basis set limit. Accounting for core-valence correlation into the wavefunction, and of anharmonic eects on the vibrational frequencies were also explored, making the results of the structural, energetic, and vibrational properties a very reliable source of data for these yet unknown species. The isomer HSeI turned out to be more stable by 42:04 kcal mol-1 than HSeI. These two isomers are separated by a barrier (ΔG#) of 52:35 kcal mol-1. Corrections arising from spin-orbit and scalar relativistic eects were also considered in the evaluation of atomization energies. For SeI, we estimate ΔfH values of 36:87 and 35:16 kcal mol-1 at 0 K and 298:15 K; for HSeI, we had 18:25 and 16:72 kcal mol-1, respectively. In general, we hope that the reliability of the results present in this work can serve as an excellent guide for spectroscopists in the search and characterization of these chemical species still unknown experimentally.
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Varner, Mychel Elizabeth. "Theoretical thermochemistry and spectroscopy of weakly bound molecules." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-08-2056.

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The weakly bound association products of atmospherically relevant radical species (O₂, OH, NO₂, HO₂ and NO) have been studied theoretically using quantum-chemical methods. The thermodynamic stabilities, which are crucial to determining the probability of formation in Earth's atmosphere, were calculated for the hydrotrioxy radical (HOOO) and peroxynitrous acid (HOONO, an isomer of nitric acid) relative to the radical dissociation products. In the case of HOONO, the experimentally determined values were confirmed. For HOOO, the predicted stability was significantly lower than the experimentally determined value; a conclusion that was supported by later experimental work and indicates that HOOO will not form in significant quantities in Earth's atmosphere. The fundamental and multi-quantum vibrational transitions were also predicted for both the HOONO and HOOO systems. The theoretical work on the HOONO system aided the assignment of experimental spectra and was used to correct equilibrium rotational constants. The HOOO system presented a challenge for the methods used here and work to apply other approaches in describing the vibrational modes is ongoing. Second-order vibrational perturbation theory, combined with a correlated quantum-chemical method and a moderately sized basis set, provides a method for accurately predicting fundamental and low-order multi-quantum transition energies and intensities for many systems (HOOO being an exception). Here coupled cluster theory, at a level which treats one- and two-electron correlation with a correction for three-electron correlation, and atomic natural orbitals basis sets were used in the vibrational calculations. To predict the dissociation energies of weakly bound species with the precision required (due to the small energy differences involved), high-order correlation contributions (a full treatment of three-electron correlation and a correction for four-electron correlation) are included, as is extrapolation to the basis set limit. Other contributions, such as that for the zero-point energy, were also considered. For the HOOO system, one-dimensional potential curves along the dissociation and torsional coordinates were constructed with standard single-reference and equation-of-motion coupled-cluster methods. The latter is better able to describe the nature of a system in the bond-breaking region and the complex electronic structure of a species formed from two radical fragments, one doubly degenerate in the ground state: X²[Pi] OH and X³[Sigma] O₂. A possible barrier to dissociation and the torsional potential for HOOO were investigated.
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9

Dearden, David Vernell. "Experimental probes of gas phase ions and molecules: I. Product kinetic energy release measurements as a probe of reaction thermochemistry, dynamics, and chemical structure in systems containing transition metal ions. II. Photoelectron and optical studies of organic transient species." Thesis, 1989. https://thesis.library.caltech.edu/554/1/Dearden_dv_1989.pdf.

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The release of kinetic energy in the decomposition of a metastable ion is a reflection of both the overall energetics and the potential energy surface on which the process takes place. Chapter 1 applies measurements of the kinetic energy release distributions (KERDs) for decomposition of metastable Mn(CO)[x][+] to the dynamics and energetics of exchange processes for the CO ligands. All the dissociations can be described by statistical phase space theory, in agreement with efficient CO exchange rates indicating that conservation of electronic spin is not important to the dynamics. A general method is presented and used whereby Mn[+]-CO bond energies are obtained from the KERDs. Chapter 2 deals with reactions of Fe[+] and Co[+] with alkanes to eliminate methane, which have KERDs narrower than predicted by statistical theory. Restriction of the angular momentum (or, equivalently, the impact parameter) to values less than those anticipated by simple ion-molecule collision theory can account for the narrowed distributions. The restrictions result from barriers in the effective potential energy surfaces and from limitations in our measurement techniques. In Chapter 3, KERDs are used to demonstrate the existence of cobaltacyclobutane[+], (hydrido)(cyclopropyl)Co[+] and Co(propene)[+] structures which do not interconvert on the µs time scale in the gas phase. Chapter 4 deals with the dehydrogenations of cyclic alkanes by Fe[+] and Co[+], and shows that, contrary to previous assumptions, statistical energy partitioning occurs in these processes. Chapters 5 and 6 deal with studies of transient organic species. Chapter 5 presents preliminary work on charge-reversed, resonance enhanced multiphoton ionization (CRREMPI), a potentially powerful new method which exploits the special characteristics of the ion cyclotron resonance spectrometer to obtain optical spectra of a wide variety of transient species. In Chapter 6 photoelectron spectroscopy is used to observe the rearrangements of primary alkyl radicals, produced by flash vacuum pyrolysis of nitrites, to the thermodynamically more stable secondary isomers. Decomposition processes are also observe
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Curtin, Larry Steven. "Doping and anion-exchange thermochemistry of polymeric and crystalline molecular conductors." 1990. http://catalog.hathitrust.org/api/volumes/oclc/22443075.html.

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1990.
Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
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Books on the topic "Thermochemistry - Molecules"

1

1963-, Irikura Karl K., Frurip David J, American Chemical Society. Division of Computers in Chemistry., and American Chemical Society Meeting, eds. Computational thermochemistry: Prediction and estimation of molecular thermodynamics. Washington, DC: American Chemical Society, 1998.

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Simões, J. A. Martinho. Molecular energetics: Condensed-phase thermochemical techniques. Oxford: Oxford University Press, 2008.

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Howe, John T. Estimates of thermochemical relaxation lengths behind normal shock waves relevant to manned lunar and Mars return missions, the aeroassist flight experiment, and Mars entry. Moffett Field, Calif: National Aeronautics and Space Administration, Ames Research Center, 1991.

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Keresü, G. M. Molecular mechanics and conformational analysis in drug design. Oxford: Blackwell Science, 1999.

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M.A.V. Ribeiro Da Silva. Thermochemistry and Its Applications to Chemical and Biochemical Systems: The Thermochemistry of Molecules, Ionic Species and Free Radicals in ... Biochemical Systems. Springer, 2011.

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Silva, M. A. V. Ribeiro Da. Thermochemistry and Its Applications to Chemical and Biochemical Systems: The Thermochemistry of Molecules, Ionic Species and Free Radicals in Relation ... Biochemical Systems. Springer, 2007.

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M.A.V. Ribeiro Da Silva. Thermochemistry and Its Applications to Chemical and Biochemical Systems: The Thermochemistry of Molecules, Ionic Species and Free Radicals in ... of Chemical and Biochemical Systems. Springer, 2011.

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M. A. V. Ribeiro Da Silva. Thermochemistry and Its Applications to Chemical and Biochemical Systems: The Thermochemistry of Molecules, Ionic Species and Free Radicals in Relation to the Understanding of Chemical and Biochemical Systems. Springer, 2012.

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Molecular Energetics: Thermochemical Techniques in Solution and Empirical Methods. Oxford University Press, USA, 2008.

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Keseru, G. M., and I. Kolossvary. Molecular Mechanics and Conformational Analysis in Drug Design. Blackwell Publishing, 1999.

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Book chapters on the topic "Thermochemistry - Molecules"

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Bohme, Diethard K. "Growing Molecules with Ion/Molecule Reactions." In Structure/Reactivity and Thermochemistry of Ions, 219–46. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3787-1_10.

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McMahon, T. B. "Assignment of Absolute Gas Phase Basicities of Small Molecules." In Structure/Reactivity and Thermochemistry of Ions, 305–20. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3787-1_16.

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Koch, Wolfram, and Helmut Schwarz. "Experimental and Theoretical Studies of Small Organic Dications, Molecules with Highly Remarkable Properties." In Structure/Reactivity and Thermochemistry of Ions, 413–65. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3787-1_21.

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Steinmetz, Marc, Andreas Hansen, Stephan Ehrlich, Tobias Risthaus, and Stefan Grimme. "Accurate Thermochemistry for Large Molecules with Modern Density Functionals." In Topics in Current Chemistry, 1–23. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/128_2014_543.

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Martin, Jan M. L. "Ab Initio Thermochemistry Beyond Chemical Accuracy for First-and Second-Row Compounds." In Energetics of Stable Molecules and Reactive Intermediates, 373–415. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4671-5_17.

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Baer, Tomas, Rick Lafleur, and Oleg Mazyar. "The Role of Ion Dissociation Dynamics in the Study of Ion and Neutral Thermochemistry." In Energetics of Stable Molecules and Reactive Intermediates, 303–22. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4671-5_14.

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Rogers, Donald W. "Molecular Mechanics in Computational Thermochemistry." In ACS Symposium Series, 119–40. Washington, DC: American Chemical Society, 1998. http://dx.doi.org/10.1021/bk-1998-0677.ch007.

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Thiel, Walter. "Thermochemistry from Semiempirical Molecular Orbital Theory." In ACS Symposium Series, 142–61. Washington, DC: American Chemical Society, 1998. http://dx.doi.org/10.1021/bk-1998-0677.ch008.

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Kraemer, W. P. "AB Initio Studies of Interstellar Molecular Ions." In Structure/Reactivity and Thermochemistry of Ions, 247–60. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3787-1_11.

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Nibbering, Nico M. M. "Organic Ion/Molecule Reactions: Summary of the Panel Discussion." In Structure/Reactivity and Thermochemistry of Ions, 401–12. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3787-1_20.

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Conference papers on the topic "Thermochemistry - Molecules"

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Gibson, John K. "Thermochemistry of Transuranium Actinide Oxide Molecules Investigated by FTICR-MS." In PLUTONIUM FUTURES - THE SCIENCE: Third Topical Conference on Plutonium and Actinides. AIP, 2003. http://dx.doi.org/10.1063/1.1594541.

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Welch, Bradley, and Richard Dawes. "APPROXIMATIONS FOR HIGH-ACCURACY THEORETICAL THERMOCHEMISTRY." In 73rd International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2018. http://dx.doi.org/10.15278/isms.2018.rj09.

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Welch, Bradley, and Richard Dawes. "A PROTOCOL FOR HIGH-ACCURACY THEORETICAL THERMOCHEMISTRY." In 72nd International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2017. http://dx.doi.org/10.15278/isms.2017.wi08.

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Lee, Kelvin, and Michael McCarthy. "HIGH ACCURACY THERMOCHEMISTRY AND KINETICS OF THE HCN/HNC SYSTEM." In 73rd International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2018. http://dx.doi.org/10.15278/isms.2018.wl10.

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Franke, Peter, and Gary Douberly. "ROTAMERS OF ISOPRENE: INFRARED SPECTROSCOPY IN HELIUM DROPLETS AND AB INITIO THERMOCHEMISTRY." In 73rd International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2018. http://dx.doi.org/10.15278/isms.2018.rg03.

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Welch, Bradley, David Bross, Branko Ruscic, Ernesto Quintas Sﾇnchez, and Richard Dawes. "EVALUATING VPT2 SCHEMES FOR ACCURATE AUTOMATED THERMOCHEMISTRY AND SPECTROSCOPY FOR NON-COVALENT SYSTEMS." In 74th International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2019. http://dx.doi.org/10.15278/isms.2019.wd05.

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Janik, Ireneusz, Ian Carmichael, and G. Tripathi. "TRANSIENT RAMAN SPECTRA, STRUCTURE AND THERMOCHEMISTRY OF THE THIOCYANATE DIMER RADICAL ANION IN WATER." In 72nd International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2017. http://dx.doi.org/10.15278/isms.2017.fc04.

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Janik, Ireneusz, and G. Tripathi. "TRANSIENT RAMAN SPECTRA, STRUCTURE AND THERMOCHEMISTRY OF THE SELENOCYANATE DIMER RADICAL ANION IN WATER." In 73rd International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2018. http://dx.doi.org/10.15278/isms.2018.fa05.

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Leavitt, Christopher, Gary Douberly, Caitlyne Shirley, Grant Moody, and Paul Raston. "VIBRATIONAL SPECTROSCOPY AND GAS-PHASE THERMOCHEMISTRY OF THE MODEL DIPEPTIDE N-ACETYL GLYCINE METHYL AMIDE." In 69th International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2014. http://dx.doi.org/10.15278/isms.2014.wi13.

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Thomas, Daniel, Gert von Helden, Gerard Meijer, Kim Greis, Maike Lettow, Eike Mucha, and Rayoon Chang. "PROBING THE CONFORMATIONAL LANDSCAPE AND THERMOCHEMISTRY OF DINUCLEOTIDE ANIONS VIA HELIUM NANODROPLET INFRARED ACTION SPECTROSCOPY." In 2021 International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2021. http://dx.doi.org/10.15278/isms.2021.tl08.

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Reports on the topic "Thermochemistry - Molecules"

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Morse, Michael D., and Peter B. Armentrout. Spectroscopy, Thermochemistry, and Reactivity of Lanthanide and Actinide Molecules. Office of Scientific and Technical Information (OSTI), August 2012. http://dx.doi.org/10.2172/1048544.

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Cole, John, Gabriel da Silva, Joseph W. Bozzelli, and William Anderson. Thermochemistry and Kinetics for Designer Molecules Additives to Energetic Materials for Improved Performance: Thermal Generation of Hydrazine. Fort Belvoir, VA: Defense Technical Information Center, September 2007. http://dx.doi.org/10.21236/ada483181.

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