• Ocean and Polar Research
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• v.26 no.3
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• pp.515-521
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• 2004

The processes of formation and dissociation of gas hydrates were investigated by monitoring pressure and temperature variations in a pressure cell in order to understand the kinetic behavior of gas hydrate and the controlling factors fur the phase transition of gas hydrate below freezing. Gas hydrates were made kom guest gases ($CH_4,\;CO_2$, and their mixed-gas) and fine ice powder. We found that formation and dissociation speeds of gas hydrates were not controlled by temperature and pressure conditions alone. The results of this study suggested that pressure levels at the formation of mixed-gas hydrate determine the transient equilibrium pressure itself.

• Bulletin of the Korean Chemical Society
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• v.15 no.3
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• pp.241-245
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• 1994

A method has been developed to estimate the kinetic energy release originating from the reverse critical energy in unimolecular ion dissociation. Contribution from the excess energy was estimated by RRKM theory, the statistical adiabatic model and the modified phase space calculation. This was subtracted from the experimental kinetic energy release distribution (KERD) via deconvolution. The present method has been applied to the KERDs in $H_2$, loss from $C_6H_6^+$ and HF loss from ${CH_2CF_2}^+$. In the present formalism, not only the energy in the reaction coordinate but also the energy in some transitional vibrational degrees of freedom at the transition state is thought to contribute to the experimental kinetic energy release. Details of the methods for treating the transitional modes are found not to be critical to the final outcome. For a reaction with small excess energy and large reverse critical energy. KERD is shown to be mainly governed by the reverse critical energy.

• JSTS:Journal of Semiconductor Technology and Science
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• v.1 no.4
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• pp.197-201
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• 2001

The influence of argon, oxygen, and nitrogen admixtures on the dissociation of $Cl_2$ molecules in a glow discharge low-temperature plasma under the constant pressure conditions was investigated. For $Cl_2/Ar$ and $Cl_2/O_2$mixtures, the concentration of chlorine atoms was observed to be a practically constant at argon or oxygen concentrations up to 50%. This invariability is a most pro bably explained by relative increase in rate of $Cl_2$ direct electron impact dissociation due to the changes in electrophysical parameters of plasma such as EEDF, electron drift rate and mean energy. For all the considered mixtures, the contribution of stepwise dissociation involving active species from gas additives (metastable atoms and molecules, vibrationally excited molecules) was found to be negligible.

• Journal of the Korean Chemical Society
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• v.55 no.5
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• pp.741-745
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• 2011

Well-resolved vibronic emission spectra were recorded in the visible region from the corona discharge of precursor alkylbenzenes in a technique of corona excited supersonic expansion using a pinhole-type glass nozzle. From the observed spectra, we found the evidence of the presence of benzyl-type radicals generated by dissociation of C-C or C-H bonds of alkyl group. After identification of benzyl-type radicals formed in the corona discharge, we suggest that energy densities in alkyl chain play a crucial role in determining the bond dissociation during corona excitation.

• Bulletin of the Korean Chemical Society
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• v.16 no.3
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• pp.256-260
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• 1995

Laser induced fluorescence spectra of OH produced from photodissociation of $H_2O_2$ at 280-290 nm in the gas phase have been observed. By analyzing the Doppler profiles, the anisotropy parameter($\beta$ =-0.7) and the center of mass translational energy of the fragments have been measured. The measured energy distribution is well described by an impulsive model. The excited state leading to dissociation is found to be of 1Au symmetry. The dissociation from this state is prompt and direct with the fragment OH rotating in the plane perpendicular to the O-O bond axis.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.04a
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• pp.111-114
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• 1996

Hydrogen generation by dissociation of water is described. The major force for the dissociation comes from the oxidation potential of the reactive metal reacting with water whereas the minor role is played by electrical discharge which helps sustain the reaction. A premixed reactive metal/water system undergoes a fast hydrogen generation upon the ignition by an electrical pulse. In another method the reactive metal can be fed into the discharge. Some characteristics of the methods are discussed.

• New & Renewable Energy
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• v.2 no.3
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• pp.37-41
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• 2006

In this study, an experimental apparatus has been designed and set up to analyze the dissociating phenomena of hydrate in porous rock. Experiments with the depressurization scheme have been carried out to investigate the dissociation characteristics of methane hydrates and the productivities of dissociated gas and water. From the experiments, it has been provided a determination of volume of gas produced and the progress of the dissociation front, as a function of time when hydrate is depressurized. Also, it has been investigated the flowing behavior of the dissociated gas and water in porous rock and the efficiency of the production

• Journal of Industrial Technology
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• v.40 no.1
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• pp.25-32
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• 2020

In this study, the effects of thermodynamic hydrate inhibitors on hydrate formation and dissociation behaviors were identified. The nucleation and growth of CP hydrate in the presence of methanol were monitored by optical microscope. Cyclopentane was used to demonstrate the oil phase in the pipeline in this study. Hydrate morphology, required time for hydrate formation, hydrate dissociation temperature were also identified by experiments. With the addition of methanol in water solution, the hydrate nucleation as well as hydrate growth were delayed. Moreover, hydrate morphology was also varied with the addition of methanol. Hydrate formation and dissociation temperature also decrease as the concentration of methanol increases.

• Bulletin of the Korean Chemical Society
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• v.35 no.10
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• pp.3021-3024
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• 2014

The potential energy surface (PES) for the dissociation of the 2-hydroxypyridine (2-HP) radical cation was determined from G3//B3LYP calculations, including the loss of CO, HCN, and HNC. The formation of the 1H-pyrrole radical cation by decarbonylation through a more stable tautomer, the 2-pyridone (2-PY) radical cation, was the most favorable dissociation pathway. Kinetic analysis by the Rice-Ramsperger-Kassel-Marcus model calculations was carried out based on the obtained PES. It is proposed that the dissociation occurs after a rapid tautomerization to 2-$PY^{{\cdot}+}$, and that most of the ions generated by ionization of 2-HP have the structure of 2-$PY^{{\cdot}+}$ at equilibrium above the tautomerization barrier.

• Bulletin of the Korean Chemical Society
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• v.31 no.9
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• pp.2588-2592
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• 2010

The potential energy surfaces (PESs) for the primary and secondary dissociations of the phenylarsane molecular ion (1a) were determined from the quantum chemical calculations using the G3(MP2)//B3LYP method. Several pathways for the loss of $H{\cdot}$ were determined and occurred though rearrangements as well as through direct bond cleavages. The kinetic analysis based on the PES for the primary dissociation showed that the loss of $H_2$ was more favored than the loss of $H{\cdot}$, but the $H{\cdot}$. loss competed with the $H_2$ loss at high energies. The bicyclic isomer, 7-arsa-norcaradiene radical cation, was formed through the 1,2 shift of an $\alpha$-H of 1a and played an important role as an intermediate for the further rearrangements in the loss of $H{\cdot}$ and the losses of $As{\cdot}$ and AsH. The reaction pathways for the formation of the major products in the secondary dissociations of $[M-H]^+$ and $[M-H_2]^{+\cdot}$. were examined. The theoretical prediction explained the previous experimental results for the dissociation at high energies but not the dissociation at low energies.