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151. An infrared study of the chemisorption of ethylene on aluminum oxide
64
Classified Abstracts
The possibility of separation of any mixture will be predictable from the th - V.C.P. curve for each component in a mixture. (In Japanese). (Author) K. Yoshimura, Japan Analyst, 11(4), April, 1962,400-406. 14 : 38 : 20 Improved molecular still and sublimer for vacuum operation. See Abstr. No. 230. 14 : 16 The effect of sorption on the kinetics of evacuation of vacuum systems. See Abstr. No. 158. 14 : 22 Construction and calibration of a cylindrical Knudsen gauge. See Abstr. No. 179.
15.
Fluid Dynamics
15 146. A 17-inch diameter shock tube for studies in rarefied gasdynamics. U.S.A. A shock tube for studying problems in rarefied gasdynamics is described. The motivation for operatingat low density (to increase the length and time scales of certain interesting flows) and the effect of low density on the performance and design of the shock tube are discussed. In order to guarantee uniform and reproducible shock waves of moderate strength, the configuration of the tube is conventional. However, innovations are introduced (for example in the suspension, the pumping system, and the diaphragm loading and rupturing mechanism) to simplify the operation. Care in the design of the tube as a vacuum system has resulted in a leak rate of less than 0.01~ Hg/h. A series of shakedown runs at relatively high pressures has shown, for example, that the reproducibility of a given shock Mach number is f 0.6 per cent. (Authors) H. W. Liepmann, 625-631.
et al., Rev.
16.
Sci. Instrum.,
33 (6), June 1962,
Gases and Solids
16 : 33 147. Determination of the diffusion parameter of hydrogen into iron and soft steel. France. An iron or steel rod of known dimensions is charged electrolytically with hydrogen for a sufficient time to ensure a uniform concentration of the gas throughout the metal. The specimen is then transferred to a vacuum chamber (1O-4 torr) at an initial temperature T of about 300°K. The sample is next heated, so that its temperature T varies linearly with time, i.e. T = To + at and the evolution of hydrogen is measured for various values of CI. The diffusion coefficient D of the gas is given by D = D, exp. (- E/KT) where K = Boltzmann constant E = activation energy of process D, = constant The authors show how D, and E can be deduced from the experimental results. Values obtained were D, = 1.7 x 10e3 cm’/sec. E = 0.22 eV/atom. w. J. s. J. Plasquellec, 51 S-520.
et al., C. R. Acad. Sci. Paris, 255 (3), 16 July 1962,
16 : 30 : 41 : 19 148. Adsorption and condensation of residual gas on cooled thin metallic films in vacuum. France. Experiments were carried out on gold films deposited on quartz and kept at a temperature of - 55°C in a vacuum of 1O-5 torr. The films had a thickness of a few hundred 8, and their optical properties (reflexion and transmission coefficient) were measured for an incident wavelength of 6OOOA. It was found
146-151
that these values varied with time and consistent results could not be obtained. A similar variation in time of the reflexion coefficient of the quartz support without the film was noted. It appears that under the conditions of the experiment, condensation and adsorption of residual gas takes place on the cooled film and support and these affect the optical properties of the surfaces. This may have been aggravated by leakage of oil vapour from the diffusion pump. w. .I. s. H. Barras, etal., C. R. Acad. Sci. Paris, 255 (7), 13 August 1962, 1213-1216. 16 :47 149. Desorption thermique pulsee de l’acier inoxydable NS-22s en ultravide. (Pulsed thermal desorption of stainless steel NS-22S in ultravacuum.) Switzerland and France. The object of the work was to obtain a detailed knowledge of the mechanisms of interaction between gases and certain solid phases used in ultra-high vacuum technology. In particular, it was desired to establish the relative importance of adsorption, desorption and diffusion of gases at the surface of stainless steel placed in a vacuum chamber. The method chosen to carry out the experiments was the flash filament technique, but it was concluded that further investigations were necessary and that additional techniques (e.g. pulsed electronic bombardment) should be applied. The authors indicate that the full text of their work is to be published later. (in French). D. A. P. L. A. Petermann, et al., Helv. Phys. Acta., 35 (4/5), Aug. 1962, 240-241. 16 150. Gas permeation study and imperfection detection of thermally grown and deposited thin silicon dioxide films. U.S.A. Methods have been developed to measure gas permeation through thin thermally grown and deposited silicon dioxide films. From the data collected it is shown that pores and microchannels (orders of magnitude smaller than pores) are formed in these films, and permeation through them is the main diffusion mechanism involved. The existence of imperfections in the oxides is demonstrated by using a chlorine etching technique. An important result from this work is that insufficient surface cleaning is an important factor in the production of relatively large pores in the oxide. Channel size approaching atomic dimensions could be obtained in these films by being extremely careful in the pre-oxidation or predeposition cleaning of the silicon. Some oxide films show the presence of crystalline structures considered to be caused by a nucleation phenomena due to the presence of foreign particles on the silicon surface. (Authors) S. W. Ing, Jr., et al., J. Electrochem. Sot., 109, March 1962, 221226. 16 151. An infrared study of the chemisorption of ethylene on aluminum oxide. U.S.A. An infrared study of the adsorption of ethylene on aluminum oxide shows several interesting features about the nature, orientation, and reactivity of the absorbed species. On some oxides, room temperature adsorption leads to the slow formation of ethyl groups S-CH,CH, (S is a surface site). The formation of CzHs involves self-hydrogenation, as the oxide contributes no hydrogen. The surface species reacts with hydrogen at 450” to give CHI, CzHR, and C3H8 in the gas phase. In contrast, on another crystallographically similar oxide, ethylene adsorption leads to the formation of S-CH,CH,-S. This species reacts with hydrogen at 450” to yield first S-CH,CH, and then gaseous C,H,. The results are discussed in terms of their significance in the general problem of elucidating the nature of the chemisorption and catalytic hydrogenation of ethylene on aluminum oxides. No chemisorption of ethylene was found to occur on silica at room temperature. (Authors) P. J. Lucchesi, et al., J. Phys. Chem., 66, Aug. 1962, 1451-1456.
Classified Abstracts
The possibility of separation of any mixture will be predictable from the th - V.C.P. curve for each component in a mixture. (In Japanese). (Author) K. Yoshimura, Japan Analyst, 11(4), April, 1962,400-406. 14 : 38 : 20 Improved molecular still and sublimer for vacuum operation. See Abstr. No. 230. 14 : 16 The effect of sorption on the kinetics of evacuation of vacuum systems. See Abstr. No. 158. 14 : 22 Construction and calibration of a cylindrical Knudsen gauge. See Abstr. No. 179.
15.
Fluid Dynamics
15 146. A 17-inch diameter shock tube for studies in rarefied gasdynamics. U.S.A. A shock tube for studying problems in rarefied gasdynamics is described. The motivation for operatingat low density (to increase the length and time scales of certain interesting flows) and the effect of low density on the performance and design of the shock tube are discussed. In order to guarantee uniform and reproducible shock waves of moderate strength, the configuration of the tube is conventional. However, innovations are introduced (for example in the suspension, the pumping system, and the diaphragm loading and rupturing mechanism) to simplify the operation. Care in the design of the tube as a vacuum system has resulted in a leak rate of less than 0.01~ Hg/h. A series of shakedown runs at relatively high pressures has shown, for example, that the reproducibility of a given shock Mach number is f 0.6 per cent. (Authors) H. W. Liepmann, 625-631.
et al., Rev.
16.
Sci. Instrum.,
33 (6), June 1962,
Gases and Solids
16 : 33 147. Determination of the diffusion parameter of hydrogen into iron and soft steel. France. An iron or steel rod of known dimensions is charged electrolytically with hydrogen for a sufficient time to ensure a uniform concentration of the gas throughout the metal. The specimen is then transferred to a vacuum chamber (1O-4 torr) at an initial temperature T of about 300°K. The sample is next heated, so that its temperature T varies linearly with time, i.e. T = To + at and the evolution of hydrogen is measured for various values of CI. The diffusion coefficient D of the gas is given by D = D, exp. (- E/KT) where K = Boltzmann constant E = activation energy of process D, = constant The authors show how D, and E can be deduced from the experimental results. Values obtained were D, = 1.7 x 10e3 cm’/sec. E = 0.22 eV/atom. w. J. s. J. Plasquellec, 51 S-520.
et al., C. R. Acad. Sci. Paris, 255 (3), 16 July 1962,
16 : 30 : 41 : 19 148. Adsorption and condensation of residual gas on cooled thin metallic films in vacuum. France. Experiments were carried out on gold films deposited on quartz and kept at a temperature of - 55°C in a vacuum of 1O-5 torr. The films had a thickness of a few hundred 8, and their optical properties (reflexion and transmission coefficient) were measured for an incident wavelength of 6OOOA. It was found
146-151
that these values varied with time and consistent results could not be obtained. A similar variation in time of the reflexion coefficient of the quartz support without the film was noted. It appears that under the conditions of the experiment, condensation and adsorption of residual gas takes place on the cooled film and support and these affect the optical properties of the surfaces. This may have been aggravated by leakage of oil vapour from the diffusion pump. w. .I. s. H. Barras, etal., C. R. Acad. Sci. Paris, 255 (7), 13 August 1962, 1213-1216. 16 :47 149. Desorption thermique pulsee de l’acier inoxydable NS-22s en ultravide. (Pulsed thermal desorption of stainless steel NS-22S in ultravacuum.) Switzerland and France. The object of the work was to obtain a detailed knowledge of the mechanisms of interaction between gases and certain solid phases used in ultra-high vacuum technology. In particular, it was desired to establish the relative importance of adsorption, desorption and diffusion of gases at the surface of stainless steel placed in a vacuum chamber. The method chosen to carry out the experiments was the flash filament technique, but it was concluded that further investigations were necessary and that additional techniques (e.g. pulsed electronic bombardment) should be applied. The authors indicate that the full text of their work is to be published later. (in French). D. A. P. L. A. Petermann, et al., Helv. Phys. Acta., 35 (4/5), Aug. 1962, 240-241. 16 150. Gas permeation study and imperfection detection of thermally grown and deposited thin silicon dioxide films. U.S.A. Methods have been developed to measure gas permeation through thin thermally grown and deposited silicon dioxide films. From the data collected it is shown that pores and microchannels (orders of magnitude smaller than pores) are formed in these films, and permeation through them is the main diffusion mechanism involved. The existence of imperfections in the oxides is demonstrated by using a chlorine etching technique. An important result from this work is that insufficient surface cleaning is an important factor in the production of relatively large pores in the oxide. Channel size approaching atomic dimensions could be obtained in these films by being extremely careful in the pre-oxidation or predeposition cleaning of the silicon. Some oxide films show the presence of crystalline structures considered to be caused by a nucleation phenomena due to the presence of foreign particles on the silicon surface. (Authors) S. W. Ing, Jr., et al., J. Electrochem. Sot., 109, March 1962, 221226. 16 151. An infrared study of the chemisorption of ethylene on aluminum oxide. U.S.A. An infrared study of the adsorption of ethylene on aluminum oxide shows several interesting features about the nature, orientation, and reactivity of the absorbed species. On some oxides, room temperature adsorption leads to the slow formation of ethyl groups S-CH,CH, (S is a surface site). The formation of CzHs involves self-hydrogenation, as the oxide contributes no hydrogen. The surface species reacts with hydrogen at 450” to give CHI, CzHR, and C3H8 in the gas phase. In contrast, on another crystallographically similar oxide, ethylene adsorption leads to the formation of S-CH,CH,-S. This species reacts with hydrogen at 450” to yield first S-CH,CH, and then gaseous C,H,. The results are discussed in terms of their significance in the general problem of elucidating the nature of the chemisorption and catalytic hydrogenation of ethylene on aluminum oxides. No chemisorption of ethylene was found to occur on silica at room temperature. (Authors) P. J. Lucchesi, et al., J. Phys. Chem., 66, Aug. 1962, 1451-1456.