- Email: [email protected]
1110. Absolute rate constants for the reaction of atomic oxygen with enthylene over the temperature range 232–500°K
Classified abstracts 1105-1117 33 1105. Scanning electron microscope investigation of ion etching of metals at oblique ion incidence. (Germany) Ion etching of a Cu surface bombarded by 10 keV Ar ions is investigated as a function of the incidence angle of ions in a scanning electron microscope. Experimental results are discussed. W Hauffe, Exper Teeh Phys, 19 (5), 1971,407-411 (in German). 33 1106. Radiation type centres generated on a dehydrated germanium surface bombarded by low energy He + ions. (USSR) It is shown that bombardment of dehydrated germanium surfaces by low energy He + ions causes an additional increase in the surface recombination rate. V G Litovchenko et al, Ukr Fiz Zh, 16 (8), 1971, 1364-1366 (in
Russian). 33 1107. Variations of electrical resistance in thin titanium films bombarded by low-energy ions. (USSR) Variations in the electrical resistance of thin titanium films under bombardment by Ar + ions with energies between 250 and 4000 eV, are investigated. The thin polycrystalline titanium films were deposited by thermal evaporation in vacuum at 2 to 8 × 10-s torr on pyrex substrates at 200°C. Regions of linearly increasing resistance, saturation and abruptly increasing resistance are found in the dependence of the resistance on the radiation dose. Variations in electrical resistance are related to the variations of structure of the films due to ion bombardment, observed with an electron microscope, and to the state of surface of the films. The experimental results help to explain the processes occurring in titanium getter-ion pumps. (Yugoslavia) B Navincek and J Karter, Zh Tekh Fiz, 41 (12), Dec 1971, 2524-2526
(in Russian). 33 1108. Self-imaging of a surface by field desorption. (Germany) Self-imaging of a tungsten surface by field desorption is studied. Using the microchannel ion-electron image conversion and 3-stage photoelectronic image intensifier, single desorbed ions are recorded. Field desorption images of the tungsten tip surface are obtained by either continually field evaporating the surface in high vacuum with a gradually increased dc voltage and taking cine- photographs or by applying microsecond evaporation pulses synchronized with the cine camera. The striking feature of a single shot field desorption microscope image is its sharpness, even at room temperature. The desorption image does not have the crystallographic regularity. Although imaging only about one third of all surface atoms, the field desorption microscopy does provide information about the sequence of field evaporation. Working at lower desorption fields the location of gaseous adsorbates is pinpointed with respect to the metal structure by comparison with a 78°K He field ion microscope image. (USA) R J Walko and E W Muller, Phys Star Sol (a), 9 (1), Jan 1972, K 9 KI0. 33 1109. Excitation of Na D-Line radiation in collision of sodium atoms with internally excited H2, D2, aud N2. (USA) Two modulated crossed beam experiments were performed in a three chamber differentially pumped vacuum. Details of the molecular and atomic beam sources, the absorption cell and velocity selectors are given. Temperatures in the range 2000-3000°K were used. In the first experiment, a total rate coefficient was measured as a function of molecular beam temperature. The second experiment achieved partial separation of internal vs kinetic energy transfer effects by using a velocity-selected molecular beam. Models are discussed to explain the observed results. H F Krause et al, J Chem Phys, 56 (9), 1st May 1972, 4593-4605. 33 1110. Absolute rate constants for the reaction of atomic oxygen with enthylene over the temperature range-232-500°K. (USA) Three techniques were used : (1) a discharge-flow system with mass spectrometric detection (2) a flash photolysis-resonance flourescence apparatus, and (3) a flash photolysis-kinetic absorption system. Within the experimental errors of the three techniques, good agreement was found for the rate constant at 298°K. The bimolecular rate constant was also found invariant to changes in both total pressure and reactant concentration. It was found that the rate data could be fitted to a simple Arrhenius expression, which is given. D D Davis et al, J Chem Phys, 56 (9), 1st May 1972, 4868-4876.
33 1111. Apparatus for studying and monitoring the emission properties of frontal oxide cathodes. (USSR) An improved form of apparatus for studying the surface of oxide cathodes and monitoring their emission is described. The apparatus is made in the form of a small electron-beam device with a screen of plane-parallel optical glass and an electron-optical system with an anode in the shape of a hollow right circular cylinder no longer than its own diameter. This arrangement yields a simple and compact device giving a high-quality electron image of the cathode with a wide range of magnification, thus facilitating the examination of the whole surface under working conditions. The cathode surface may be examined, in particular, during such transient processes as activation, conditioning, and life tests. The cost of monitoring oxide cathodes is reduced by a factor of five on using this apparatus. B V Katsnelson et al, USSR Patent No 311314, appl 19th Sept 1969, publd 22nd Oct 1971. 37. METALLURGY, INORGANIC CHEMISTRY, ANALYTICAL CHEMISTRY 37 1112. Cell for absorption spectroscopy in temperature interval from --180 to 100°C. (Germany) A cell for absorption optical spectroscopy is described, which can be used for investigations of chemical reactions in the temperature interval of 180 to 100°C. The cell consists of a vacuum enclosure, heating equipment and sample holder. The determined temperature is maintained by the heater with setting of the pressure in the vacuum enclosure beginning from several 10-4 torr. W Regenstein, Exper Tech Phys, 19 (4), 1971, 303-305 (in German). 37 1113. Electron microscopic studies of the Laves phases TiCr2 and TiCo~. (Germany) The Laves phases TiCr2 and TiCo2 were examined in an electron microscope. The alloys were prepared by melting the constituents under vacuum in a closed system. Polytypism was found in the investigated Laves phases. C W Allen et al, Phys Stat Sol (a). 9 (1), Jan 1972, 237-246. 37 1114. Influence of arsenic vapour pressure on germanium diffusion in gallium arsenide. (USSR) Influence of arsenic vapour pressure on germanium diffusion in gallium arsenide is investigated in the As vapour pressure range of 10-2 to 3 atmospheres. Experimental results are discussed. T T Lavrischev and S S Khludkov, Neorg Mater, 7 (2), 1971, 310-311
(in Russian). 37 1115. Growth conditions and morphological peculiarities of gallium phosphide whiskers obtained by thermal evaporation in vacuum. (Germany) Gallium phosphide whisker crystals were grown by thermal evaporation in vacuum in a closed volume. Gallium phosphide crystal powder synthesized from a melt solution was used as starting material. The whiskers were grown in an evacuated to 10-6 torr ampoule of fused quartz previously thoroughly cleaned and degassed. It is found that the crystals grow preferably along (100), (110), (111) and (112) directions. The crystallization mechanism from the gaseous phase through an intermediate liquid layer is observed when an excess of gallium is introduced. Various questions connected with possible growth mechanisms of gallium phosphide are discussed. Using an electron microscope, the structure of the whiskers obtained was studied and a high degree of perfection was found. (USSR) P O Barabtarlo et al, Phys Stat Sol (a), 8 (2), Dec 1971, 521-529. 37 1116. Electron concentration and mobility in CdS single crystals. (Germany) n-type CdS crystals were grown by a sublimation method in a quartz evacuated ampoule sealed under 10-5 torr. Hall effect and conductivity in the crystals were measured in the temperature range from 80 to 400°K. (Hungary) B Podor et aI, Phys Stat Sol(a), Dec 1971, 613-624. 37 1117. Differential diffusion-sorption analysis. (USSR) The method of differential diffusion-sorption analysis is used for determination of composition of gaseous mixtures of H~, N~, COs and 431
Russian). 33 1107. Variations of electrical resistance in thin titanium films bombarded by low-energy ions. (USSR) Variations in the electrical resistance of thin titanium films under bombardment by Ar + ions with energies between 250 and 4000 eV, are investigated. The thin polycrystalline titanium films were deposited by thermal evaporation in vacuum at 2 to 8 × 10-s torr on pyrex substrates at 200°C. Regions of linearly increasing resistance, saturation and abruptly increasing resistance are found in the dependence of the resistance on the radiation dose. Variations in electrical resistance are related to the variations of structure of the films due to ion bombardment, observed with an electron microscope, and to the state of surface of the films. The experimental results help to explain the processes occurring in titanium getter-ion pumps. (Yugoslavia) B Navincek and J Karter, Zh Tekh Fiz, 41 (12), Dec 1971, 2524-2526
(in Russian). 33 1108. Self-imaging of a surface by field desorption. (Germany) Self-imaging of a tungsten surface by field desorption is studied. Using the microchannel ion-electron image conversion and 3-stage photoelectronic image intensifier, single desorbed ions are recorded. Field desorption images of the tungsten tip surface are obtained by either continually field evaporating the surface in high vacuum with a gradually increased dc voltage and taking cine- photographs or by applying microsecond evaporation pulses synchronized with the cine camera. The striking feature of a single shot field desorption microscope image is its sharpness, even at room temperature. The desorption image does not have the crystallographic regularity. Although imaging only about one third of all surface atoms, the field desorption microscopy does provide information about the sequence of field evaporation. Working at lower desorption fields the location of gaseous adsorbates is pinpointed with respect to the metal structure by comparison with a 78°K He field ion microscope image. (USA) R J Walko and E W Muller, Phys Star Sol (a), 9 (1), Jan 1972, K 9 KI0. 33 1109. Excitation of Na D-Line radiation in collision of sodium atoms with internally excited H2, D2, aud N2. (USA) Two modulated crossed beam experiments were performed in a three chamber differentially pumped vacuum. Details of the molecular and atomic beam sources, the absorption cell and velocity selectors are given. Temperatures in the range 2000-3000°K were used. In the first experiment, a total rate coefficient was measured as a function of molecular beam temperature. The second experiment achieved partial separation of internal vs kinetic energy transfer effects by using a velocity-selected molecular beam. Models are discussed to explain the observed results. H F Krause et al, J Chem Phys, 56 (9), 1st May 1972, 4593-4605. 33 1110. Absolute rate constants for the reaction of atomic oxygen with enthylene over the temperature range-232-500°K. (USA) Three techniques were used : (1) a discharge-flow system with mass spectrometric detection (2) a flash photolysis-resonance flourescence apparatus, and (3) a flash photolysis-kinetic absorption system. Within the experimental errors of the three techniques, good agreement was found for the rate constant at 298°K. The bimolecular rate constant was also found invariant to changes in both total pressure and reactant concentration. It was found that the rate data could be fitted to a simple Arrhenius expression, which is given. D D Davis et al, J Chem Phys, 56 (9), 1st May 1972, 4868-4876.
33 1111. Apparatus for studying and monitoring the emission properties of frontal oxide cathodes. (USSR) An improved form of apparatus for studying the surface of oxide cathodes and monitoring their emission is described. The apparatus is made in the form of a small electron-beam device with a screen of plane-parallel optical glass and an electron-optical system with an anode in the shape of a hollow right circular cylinder no longer than its own diameter. This arrangement yields a simple and compact device giving a high-quality electron image of the cathode with a wide range of magnification, thus facilitating the examination of the whole surface under working conditions. The cathode surface may be examined, in particular, during such transient processes as activation, conditioning, and life tests. The cost of monitoring oxide cathodes is reduced by a factor of five on using this apparatus. B V Katsnelson et al, USSR Patent No 311314, appl 19th Sept 1969, publd 22nd Oct 1971. 37. METALLURGY, INORGANIC CHEMISTRY, ANALYTICAL CHEMISTRY 37 1112. Cell for absorption spectroscopy in temperature interval from --180 to 100°C. (Germany) A cell for absorption optical spectroscopy is described, which can be used for investigations of chemical reactions in the temperature interval of 180 to 100°C. The cell consists of a vacuum enclosure, heating equipment and sample holder. The determined temperature is maintained by the heater with setting of the pressure in the vacuum enclosure beginning from several 10-4 torr. W Regenstein, Exper Tech Phys, 19 (4), 1971, 303-305 (in German). 37 1113. Electron microscopic studies of the Laves phases TiCr2 and TiCo~. (Germany) The Laves phases TiCr2 and TiCo2 were examined in an electron microscope. The alloys were prepared by melting the constituents under vacuum in a closed system. Polytypism was found in the investigated Laves phases. C W Allen et al, Phys Stat Sol (a). 9 (1), Jan 1972, 237-246. 37 1114. Influence of arsenic vapour pressure on germanium diffusion in gallium arsenide. (USSR) Influence of arsenic vapour pressure on germanium diffusion in gallium arsenide is investigated in the As vapour pressure range of 10-2 to 3 atmospheres. Experimental results are discussed. T T Lavrischev and S S Khludkov, Neorg Mater, 7 (2), 1971, 310-311
(in Russian). 37 1115. Growth conditions and morphological peculiarities of gallium phosphide whiskers obtained by thermal evaporation in vacuum. (Germany) Gallium phosphide whisker crystals were grown by thermal evaporation in vacuum in a closed volume. Gallium phosphide crystal powder synthesized from a melt solution was used as starting material. The whiskers were grown in an evacuated to 10-6 torr ampoule of fused quartz previously thoroughly cleaned and degassed. It is found that the crystals grow preferably along (100), (110), (111) and (112) directions. The crystallization mechanism from the gaseous phase through an intermediate liquid layer is observed when an excess of gallium is introduced. Various questions connected with possible growth mechanisms of gallium phosphide are discussed. Using an electron microscope, the structure of the whiskers obtained was studied and a high degree of perfection was found. (USSR) P O Barabtarlo et al, Phys Stat Sol (a), 8 (2), Dec 1971, 521-529. 37 1116. Electron concentration and mobility in CdS single crystals. (Germany) n-type CdS crystals were grown by a sublimation method in a quartz evacuated ampoule sealed under 10-5 torr. Hall effect and conductivity in the crystals were measured in the temperature range from 80 to 400°K. (Hungary) B Podor et aI, Phys Stat Sol(a), Dec 1971, 613-624. 37 1117. Differential diffusion-sorption analysis. (USSR) The method of differential diffusion-sorption analysis is used for determination of composition of gaseous mixtures of H~, N~, COs and 431