Absorption Activation Energy Research Articles

Solubility and diffusion of methane in coal strata

The authors study the solubility and diffusion of methane in coal strata and determine the absorption activation energy of methane experimentally between 133 and 323/sup 0/K. These experiments were made on samples of coal, degassed at 60/sup 0/C. The relation between initial and equilibrium swelling of anthracites in carbon dioxide is shown. The sorption of methane by superanthracites is also presented.

Recovery and Storage of Tritium by Zr-V-Fe Getter

The rates of ab/desorption of water vapor for zr-V-Fe getter were investigated by means of mass analyzed thermal desorption spectroscopy. The absorption rate obeyed first order kinetics with respect to the pressure of water vapor. The activation energies for absorption were determined as 1.8 (H/sub 2/O), 2.7 (D/sub 2/O), and 3.2 (T/sub 2/O) kcal/mol. Only hydrogen was desorbed by heating the getter in which water was absorbed. The desorption obeyed second order kinetics with respect to the amount of absorption. The activation energies for desorption were determined as 28.0 (H/sub 2/O), 28.6 (D/sub 2/O), and 29.3 (T/sub 2/O) kcal/mol. It is concluded that the rate determining step for absorption is the dissociation reaction of adsorbed water molecules or hydroxyl groups on the surface. The rate determining step for desorption is the association reaction of hydrogen atoms which diffuse from the bulk to the surface.

Recovery and storage of tritium by Zr-V-Fe getter

The rates of ab/desorption of water vapor for zr-V-Fe getter were investigated by means of mass analyzed thermal desorption spectroscopy. The absorption rate obeyed first order kinetics with respect to the pressure of water vapor. The activation energies for absorption were determined as 1.8 (H/sub 2/O), 2.7 (D/sub 2/O), and 3.2 (T/sub 2/O) kcal/mol. Only hydrogen was desorbed by heating the getter in which water was absorbed. The desorption obeyed second order kinetics with respect to the amount of absorption. The activation energies for desorption were determined as 28.0 (H/sub 2/O), 28.6 (D/sub 2/O), and 29.3 (T/sub 2/O) kcal/mol. It is concluded that the rate determining step for absorption is the dissociation reaction of adsorbed water molecules or hydroxyl groups on the surface. The rate determining step for desorption is the association reaction of hydrogen atoms which diffuse from the bulk to the surface.

Temperature-programmed absorption of hydrogen in palladium powder

Temperature-programmed absorption of hydrogen in palladium powder is used to determine the activation energy of absorption at low hydrogen concentrations. In this technique the amount of hydrogen absorbed by the palladium is measured as a function of temperature which is increased linearly in time. This technique is suitable in a temperature region where the hydrogen absorption rate is very low. We have found that the activation energy is 15.9 ± 1.3 kJ (mol H 2) −1 for absorptions in the temperature region 130–160 K. This value is in agreement with that obtained by calorimetric measurements made by Couper and John for the same temperature region. However, it is lower than the value obtained by measuring the variations in the electrical resistance during the absorption of low amounts of hydrogen into a phase palladium foil at room temperature and above.

ミッシュメタル－ニッケル系合金の水素吸・脱蔵特性

The equilibrium hydrogen absorption and desorption pressures, the hydrogen absorption and desorption rates, and the other characteristics of Mm-Ni alloys have been studied to appraise as hydrogen storage materials. In this study, it is clear that Mm-Ni alloys have good practical characteristics. Mm-Ni alloys containing 65 to 67 wt%Ni absorb the maximum amounts of hydrogen in the Mm-Ni system. For example, Mm-67 wt%Ni alloy forms the hydride MmNi4.95H6.95 at 20°C, and the equilibrium hydrogen absorption and desorption pressures are 20 and 10 atm respectively. The enthalpy changes of hydride formation and dissociation for Mm-67 wt%Ni alloy are −5.0 and 4.1 kcal/mol, and the apparent activation energies of hydrogen absorption and desorption are 6.1 and 8.6 kcal/mol respectively.

還元性雰囲気下におけるCaO-SiO<SUB>2</SUB> 2元系スラグの窒素吸収

This study was made on the absorption of nitrogen in CaO-SiO2 binary slag with or without carbon saturated iron. The rate of silicon transfer from slag to metal was also measured.The apparent activation energy of nitrogen absorption was about 150 kcal/mol. The rate of nitrogen absorption increased as the activity of lime, the slag-graphite interfacial area, and the initial content of silicon in metal increased. The nitrogen absorption which depended on the slag-metal interface was accelerated with decrease in its area. These results suggest that the reaction of nitrogen absorption proceeds electrochemically and its rate is controlled by a chemical reaction.The present results on the reaction of silica reduction agreed with the previous reports studied under an atmosphere of carbon monoxide or argon.As the cathodic current for silica reduction was much larger than that for nitrogen absorption, it was supposed that the mixed potential of system was approximately determined by the large polarization of silica reduction. Therefore, the rate of nitrogen absorption was considered to be greatly affected by the reaction of silica reduction.

Ordering of guest-molecule dipoles in the structure I clathrate hydrate of trimethylene oxides

The rotational mobility of encaged trimethylene oxide (TMO) molecules was studied down to 1.8°K by sub-MHz dielectric measurements of the structure I H 2O clathrate and by proton magnetic resonance measurements of the corresponding D 2O clathrate. The results indicate that below a transitional temperature range about 105°K most TMO dipoles assume parallel alignment along the 4 axes of the cages. Below the transition the proton second moment suggests the presence of hindered rotation of TMO about its polar axis until the rigid-lattice condition is reached below 5°K. Some residual very broad dielectric absorption (activation energy 2.1 kcal/mole) persists to very low temperatures. Guest-guest and guest-host interaction energies are calculated for simple models

Linear relation between ultraviolet absorption transition energies and activation energies for thermal isomerization of cyclic olefins

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLinear relation between ultraviolet absorption transition energies and activation energies for thermal isomerization of cyclic olefinsJohn E. Baldwin and A. Harry AndristCite this: J. Am. Chem. Soc. 1971, 93, 13, 3289–3290Publication Date (Print):June 1, 1971Publication History Published online1 May 2002Published inissue 1 June 1971https://doi.org/10.1021/ja00742a035RIGHTS & PERMISSIONSArticle Views35Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (265 KB) Get e-Alerts Get e-Alerts

Absorption Kinetics of Nitrogen+Tantalum System

The dependence of the absorption rate on temperature is studied for a single-crystal tantalum wire, and is compared with those for polycrystal wires and ribbons. Two processes of absorption of nitrogen in tantalum are found. In the first process absorption occurs at boundaries of crystal grains and is observed for polycrystal ribbons with surface of the (311) planes; the activation energy of absorption is 1.9 eV/2-atoms. The second process is observed for crystallized or sufficiently flashed wires. In this process atoms chemisorbed on the surface are directly absorbed into the bulk at their absorption sites; the activation energy of absorption is 4.0 eV/2-atoms, which is larger than that of diffusion of nitrogen in tantalum.

Chemisorption and Absorption of Nitrogen with Tantalum

Sorption of nitrogen on polycrystal tantalum ribbons is studied using a static method in ultra-high vacuum. Saturation coverage is 3.6×1014 molecules/cm2. Sticking probability at room temperature is 0.17 UP to 1.4×1014 molecules/cm2, and abruptly falls to 0.03 at about 2×1014 molecules/cm2. This suggests the existence of multiplex adsorption states in this system. The absorption occurs at temperatures above 500°K, so the desorption from the chemisorption states is not observed. From an analysis of the absorption rate, the nitrogen atoms chemisorbed on the surface of the polycrystal ribbon is shown to be absorbed at the grain boundary. The activation energy of absorption is 1.8 eV/2-atoms, and is much smaller than that of diffusion of nitrogen in tantalum. As the concentration of nitrogen in tantalum is proportional to the square root of equilibrium pressure, nitrogen is absorbed in atomic form into the bulk. Desorption from the absorption state is observed at temperatures above 1800°K. The heat of absorption is 4.4 eV in the pressure range from 10-8 to 10-2 Torr.

Space charge conduction and electrical behaviour of aluminium nitride single crystals

Hall mobility, optical absorption and thermal activation energy have been measured on single crystals of aluminium nitride grown from the vapour phase. Colourless crystals have a resistivity of about 10 12 ohm cm and behave in a strongly non-ohmic manner for large applied fields. Blue crystals have a resistivity of about 10 4 ohm cm and are p-type.

The Activation Energy of Bromine Absorption by Carbonaceous Materials

Abstract In the present paper, the temperature dependence of the rate of bromine absorption by the carbonaceous materials has been studied. The apparent energies of activation of the reaction have been found to be 5∼7 kcal./mol. and had a dependence upon the degree of graphitization of carbonaceous materials. The value of the activation energy became smaller with an increase in the degree of graphitization. The results indicate that the mobilities of reactant molecules of the interlamellar compounds increase with the growth of the net plane of graphite crystals. The saturation concentration of bromine in carbonaceous materials, under a saturated vapor pressure of bromine, was found to decrease with an increase in the temperature at temperatures above 30°C.

Anionlücken und Zwischengitterionen in Alkalihalogenid-Alkalihydrid-mischkristallen

Irradiation with u.v. light, at low temperatures, of KCl, KBr, KI and RbCl crystals containing hydride ion centres (substitutional H −; U-centers) causes the destruction of the hydride ion centres accompanied by the creation of both anion vacancies and another type of centre (H − i). H − i-centres show an infrared vibrational absorption in the region near 12μ, the frequency of which is l.7-1.9 times higher than the absorption frequency of the hydride ion centres. The H − i absorption shows a complicated structure when measured at 20°K. Further investigation demonstrates that there are several types of H − i-centres present, each type contributing, in general, a group of 3 lines to the total spectrum. The existence of these different types of H − i-centres is established by the fact that certain groups of lines have a characteristic annealing temperature. The splitting of the lines in one group tends to increase with decreasing activation energy for recombination of the corresponding centres with anion vacancies. The activation energies for the different types of centres vary between 0.3 and 0.5 eV in both KCl and KBr crystals, according to preliminary measurements. An explanation for the behaviour of the H − i-centres is given on the basis of a model in which an H − ion occupies different interstitial sites in the vicinity of an anion vacancy. A separation of 1̃0 a ( a = nearest-neighbor distance) between H − i ions and vacancies should be sufficient to suppress the influence of the vacancy on the absorption frequency and activation energy.

Measurement of gas evolution and absorption from materials used in vacuum tubes

As a first step of their study on the gas-evolution from materials used in vacuum tubes, the writers took up three methods of measuring in common use, namely, the gas accumulation, the gas flow (differential Pirani gauge) method, and the flowmeter method. The writers, while reviewing the principles of these methods, discussed their sensitivities in relation to various gases, and mentioned difficulties in experimenting with low pressure gases, especially the outgas from the glass wall and other parts of the vacuum system as well as the reaction between the sample material and the gases evolved from it. On the basis of the experimental results, the writers have developed the gas evolution and adsorption gauges on the gas flow method, which record the measurement automatically. Some examples of the actual measurement of outgas characteristics of metal plates are given in this report. The characteristics of the gas absorption of titanium has many interesting problems and it suggests useful applications in the field of the vacuum tube production. The writers also carried out the experiment for studying the gas absorption rate of titanium for such gases as nitrogen, oxygen, carbon mon- and dioxide, at various temperatures. The pressure of the gas sealed in a vessel and contacted with the titanium surface decreased exponentially with time in the pressure range of this experiment, and then it is concluded that the absorption speed is nearly constant. From its dependence the activation energies of absorption for these gases were calculated. Moreover, some interesting phenomena such as the hysteresis effect of gas absorption and the jump of speed which occurred abruptly in the process of the carbon dioxide absorption were found.

チタンのガス吸収について

Gas absorption characteristics of titanium have many interesting problems and they suggest useful applications in the field of vacuum engineerings. Experiments have been carried out for studying the gas absorption rate of titanium for such gases, nitrogen, oxygen, carbon mono-and dioxide. at various temperatures. The pressure of gas, sealed in a vessel and cont octed with titanium surface, decrease exponentially with time in the pressure range of this experiment and then it is concluded that the absorption speed is nearly constant.-from its temperature dependency the activation energies of absorption for these gases are calculated. Moreover, some interesting phenomena, such as hysteresis effect of gas absorption and jump of speed which is occured abruptly in the process of carbon dioxide absorption, are found.

A Logarithmic Function Evidencing a Correlation between Absorption Lines and Activation Energies.

A Logarithmic Function Evidencing a Correlation between Absorption Lines and Activation Energies.