Browsing by Author "Takaishi, T."

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Adsorption of Krypton on Alkali Halide Crystals Part 2.—On NaCI, KC1 and RbCl
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (10), 1972) Takaishi, T.
Adsorption of krypton on NaCI, KC1 and RbCl was measured at temperatures controlled to within ±0.005 K in the range 70-85 K. The equilibrium pressure was measured with a precision better than 0.5 % by carefully correcting for the thermal transpiration effect. Adsorption isotherms showed 2-dimensional condensation, and the critical temperatures of the 2-dimensional film were 80.0, 76.0 and 75.5 K for NaCI, KC1 and RbCl, respectively. Curves of the isosteric heat of adsorption against coverage had a unique form, and were analyzed by a model consisting of two kinds of domain of adsorption sites with a patchy structure. The lateral interaction energy between adsorbates was obtained from a?st against 0 curve, and the term of the third body effect was deduced by the method given in Part 1. Analyzing this term further, the surface electric field was estimated; the field strength on the adsorption site was of the order of 109 V/m. According to the results of Part 1, this means that the adsorption site is the C-site (above cation), and that the surface lattices of KC1 and RbCl are distorted as postulated by Benson and his coworkers. The entropy of adsorbates was analyzed on the basis of the localized adsorption model. The thermal (non-configurational) entropy of adsorbate obtained had reasonable values, supporting the assumed model. Finally, the origin of the surface heterogeneity is discussed.
Adsorption of Krypton on Alkali Halide Crystals: Part 1.—Theory
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (5), 1972) Takaishi, T.
The adsorption of krypton on alkali halide crystals with the NaCl-type structure has been studied theoretically in order to analyze detailed experimental data given in a succeeding paper. Emphasis was placed on the mutual interaction between adsorbates, perturbed by the solid adsorbent (the third body effect). Changes of lateral vibrational state of the adsorbed krypton with coverage were taken into consideration in deriving an adsorption isotherm. An analysis is given of the third body effect in the localized adsorption model, and an equation derived which correlates the third body effect with the surface electric field. Using this equation, one can estimate the order of magnitude of the field strength, and, in favourable cases, verify the existence of the distortion of the surface lattice postulated by Benson and coworkers.
Motional State of Sorbed Nitrogen in Mordenite
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (1-6), 1974) Takaishi, T.; Yusa, A.; Ogino, Y.
Sorption isosteres of nitrogen in mordenite have been accurately measured by a gravimetric method over a temperature range – 50 to 25°C. Sorption isotherms at 25, 50 and 75°C have also been measured by the use of a high pressure adsorption apparatus. Analysis of the experimental results by statistical mechanics, allows the thermal entropy of the sorbed nitrogen to be obtained as a function of temperature. It is well established, from entropy values, that the sorbed nitrogen is in a librational state at temperatures below – 20°C and freely rotating above 20°C. The transition from libration to free rotation occurs over a narrower temperature range than for the internal rotation of a molecule. The equation of state for sorbed nitrogen is derived, and values for its virial coefficients are compared with those for gaseous nitrogen and discussed qualitatively in the light of the molecular theory of fluids.