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Investigation of electronic properties of surface after adsorption of various gases by the method of exoelectron emission.
Classified
abstracts
690-700
mass spectrometer, oxygen interaction kinetics with tantalum arc investigated at oxygen pressure of lo-’ torr and over the temperature range 300 to 2400°K. The tantalum filament was cleaned by heating in vacuum at IO-!’ torr. The only observed product of desorption was TaO desorbed in the form of single phase. The apparent sticking coefficient of oxygen was independent of the degree of coverage at coverages below 1 and above 1.5, with adsorbent temperatures below 1100 K, and for all coverages above I100 K. The sticking coefficient was independent of temperature at coverages below 1 and temperatures above II00 K. The sticking coefficient considerably increases with temperature enhancement above 1100 K. A model for calculation of the dependence of the sticking coefficient on the coverage degree is presented which is based on existence of an intermediate state of adsorbed molecules. A calculation of the dependence of amount of oxygen adsorbed by tantalum is presented which is based on the assumption that the oxygen adsorption rate on tantalum is determined by processes on the boundary metal-gas. V N Ageev and N I Ionov, Fiz Twcl Tdu, 13 (6), 197 I, 1557-l 563 (bl RWWifD7). 16 690. Simultaneous adsorption of atoms of scandium and oxygen on the (110), (100) and (111) faces of single crystal tungsten. (USSR) Using the method of thermionic emission, variations in the work functions of the (1 IO), (100) and (111) faces of tungsten are investigated for the adsorption of scandium atoms in the absence of oxygen, and with subsequent adsorption of oxygen, at oxygen partial pressure of 5;\ 10m7 torr, on the scandium films. The tungsten single crystal and scandium source were cleaned in vacuum at lo-!’ torr to lo-” torr at 2300 and 1500”K, respectively. Experimental results are discussed. 0 K Kultashev and A P Makarov, Zzv AN SSSR SW Fiz, 35 (2), 1971, 35 l-354 (in RNs,siu/?). 16 691. Adsorption of yttrium atoms on single crystal tungsten. (USSR) Using the methods of field electron emission, contact potential difference and low-energy electron diffraction, adsorption of yttrium on single crystal tungsten is investigated. Dependence of the work function of single crystal tungsten faces on the concentration of yttrium adatoms is measured at different substrate temperatures. The experimental data indicate the important role of repulsive interaction between yttrium atoms in the first monolayer. V B Voronin and A G Naumovets, Izv AN SSSR SEI. Fiz, 35 (2), 1971, 355-35X (in Russian). 16 692. Quasi-molecular model of chemisorption on the surface of an ionic crystal. (USSR) Formulae for energies of optical and thermal activation of electrons from the local level, produced by chemisorption on the surface of an ionic crystal, to the bottom of the conduction band, are considered and compared with experimental data. M I Molotskiy and A N Latyshev, IZYAN SSSR SW Fiz, 35 (2), I97 1, 359-360 (in Russia/z). 16 693. Investigation of some sorption processes on a tantalum getter in an atmosphere of carbon monoxide. (Poland) Conditions of sorption of residual gases on tantalum are investigated. A dependence of the carbon monoxide partial pressure on the temperature of the tantalum filament is found. Optimum carbon monoxide sorption on tantalum occurs at 125O’C, while at 85O’C sorption does not take place. The maximum desorption is observed at 16OO’C and above this temperature sorption again increases. Causes of this behaviour are not explained. A Pietraniec and P Chocisnowski, Zesz Narrk P C’zcst, No 66, I97 I, I 5-20 (in Pdish). 16 : 18 of electronic properties of surface after adsorption of various gases by the method of exoelectron emission. (USSR) Exoelectron emission from surface of ;J-aluminium oxide at 300 K IS investigated before and after adsorption of H,, CO, and N,O. it is shown that adsorption of H, results in enhancement of exoemission, while adsorption of CO, and N,O considerably reduces exoelectron emission. Experimental results are discussed. D 1 Baazov et al, Izv AN SSSR SW I?‘,-, 35 (2). 1971, 361-365 (i/f RWWiU,!). 694. Investigation
240
16 : 18 695. Mechanism of action of oxygen on properties of Ag-0-Cs photocathode. (USSR) Variations in electrical conductivity, thermionic and photoelectron emission, electron affinity and thermionic work function of the Ag-0-Cs photocathode are studied at different stages of its sensitization by oxygen. The mechanism of oxygen action on these parameters is considered. M T Pakhomov and A E Melamid, Iz,, AN SSSR SW Fiz, 35 (2). 197 I, 307.-3 I4 (i/r Russicul). 16 : 37 696. Arrangement for investigation of the diffusion coefficient, permea(USSR) tion and solubility of hydrogen and deuterium in metals. A vacuum system with base pressure of 10e5 torr for simultaneous measurement of the diffusion coefficient and permeation of hydrogen in metals over the broad temperature range of 200 to 900°C is described. Three McLeod gauges are used in the measuring sections. V A Goltsov et al, Zavorlsk Lab, 37 (6), 1971, 740-741 (in Russian).
18. GASEOUS
ELECTRONICS
I8 697. Adsorption-emission characteristics of films of rare earth metals (USSR) on faces of single crystal tungsten. Using sealed field emission and emission spherical microscopes, adsorption of Y, La, Cd, Ce and Eu on faces of single crystal tungsten is investigated in vacuum at 1 s lo-$ torr. Work function and heat of evaporation of adsorbed films are determined. It is found that the most active system is La on (I 11)and (116) W faces. A V Garnov et al, Iz\, AN SSSR Ser Fiz, 35 (2), 1971, 341-344 (in Rlr.wiu/r). I8 698. Threshold theory of influence of adsorption on field and photoelectron emission. (USSR) Changes in the dependence of the emission current on external electric field and in the energy distribution of emitted electrons caused by adsorption on surface of emitter are considered. Influence of adsorption on field and photoelectron emission is studied with respect to the discrete structure of the adsorbed layer. A M Brodskiy et al, Izv AN SSSR Ser Fiz, 35 (2), 1971, 366-372 (in Russian). 18 699. Light-stimulated secondary electron emission and investigation of (USSR) adsorption processes by the photoelectron emission method. The simultaneous action of illumination and electron bombardment on polycrystalline silver is investigated in a glass device of the spherical capacitor type at a residual gas pressure of lo-” torr. It is found that the resulting emission current is smaller than the sum of the photocurrent and the secondary emission current measured separately. Adsorption processes are studied with the aid of a highvacuum photo-emission microscope with magnification of 75 to 150 and residual gas pressure of IO-* torr. The process of deposition of BaO active material on MO metallic substrate was observed. It is found that the initial stage of adsorption takes place on irregularities of substrate surface. Variations in image contrast with further evaporation of BaO on MO, are observed. I Buribaev and B B Shishkin, Izv AN SSSR Ser Fiz, 35 (2), I97 1, 323% 326 (a Rmiun). I8 700. Influence of radiation and dimensions of samples on breakdown characteristics on the surface of an epoxy compound in vacuum. (USSR) Analysis of results of measurements and investigations of sample surfaces after vacuum breakdown show that non-irradiated epoxy compound insulators are resistant against cracking. After multiple flashovers with discharge currents of 0.5 to 1 A no traces of disturbance were observed on epoxy insulators. The voltage of flashover remained high after many flashovers on surface of the samples. Breakdown characteristics of epoxy surfaces in vacuum are very good. The electrical insulation properties of epoxy surfaces are preserved at absorption of doses up to 10” rad. Epoxy compound is recommended as an insulator material suitable for application in ~aciiiim systems. S D Isdmukhamedov et al, DohI Akutl Nurrk Uzbec SSR, No 6, 1971, 30~32 (i/r R~~s.sim).
abstracts
690-700
mass spectrometer, oxygen interaction kinetics with tantalum arc investigated at oxygen pressure of lo-’ torr and over the temperature range 300 to 2400°K. The tantalum filament was cleaned by heating in vacuum at IO-!’ torr. The only observed product of desorption was TaO desorbed in the form of single phase. The apparent sticking coefficient of oxygen was independent of the degree of coverage at coverages below 1 and above 1.5, with adsorbent temperatures below 1100 K, and for all coverages above I100 K. The sticking coefficient was independent of temperature at coverages below 1 and temperatures above II00 K. The sticking coefficient considerably increases with temperature enhancement above 1100 K. A model for calculation of the dependence of the sticking coefficient on the coverage degree is presented which is based on existence of an intermediate state of adsorbed molecules. A calculation of the dependence of amount of oxygen adsorbed by tantalum is presented which is based on the assumption that the oxygen adsorption rate on tantalum is determined by processes on the boundary metal-gas. V N Ageev and N I Ionov, Fiz Twcl Tdu, 13 (6), 197 I, 1557-l 563 (bl RWWifD7). 16 690. Simultaneous adsorption of atoms of scandium and oxygen on the (110), (100) and (111) faces of single crystal tungsten. (USSR) Using the method of thermionic emission, variations in the work functions of the (1 IO), (100) and (111) faces of tungsten are investigated for the adsorption of scandium atoms in the absence of oxygen, and with subsequent adsorption of oxygen, at oxygen partial pressure of 5;\ 10m7 torr, on the scandium films. The tungsten single crystal and scandium source were cleaned in vacuum at lo-!’ torr to lo-” torr at 2300 and 1500”K, respectively. Experimental results are discussed. 0 K Kultashev and A P Makarov, Zzv AN SSSR SW Fiz, 35 (2), 1971, 35 l-354 (in RNs,siu/?). 16 691. Adsorption of yttrium atoms on single crystal tungsten. (USSR) Using the methods of field electron emission, contact potential difference and low-energy electron diffraction, adsorption of yttrium on single crystal tungsten is investigated. Dependence of the work function of single crystal tungsten faces on the concentration of yttrium adatoms is measured at different substrate temperatures. The experimental data indicate the important role of repulsive interaction between yttrium atoms in the first monolayer. V B Voronin and A G Naumovets, Izv AN SSSR SEI. Fiz, 35 (2), 1971, 355-35X (in Russian). 16 692. Quasi-molecular model of chemisorption on the surface of an ionic crystal. (USSR) Formulae for energies of optical and thermal activation of electrons from the local level, produced by chemisorption on the surface of an ionic crystal, to the bottom of the conduction band, are considered and compared with experimental data. M I Molotskiy and A N Latyshev, IZYAN SSSR SW Fiz, 35 (2), I97 1, 359-360 (in Russia/z). 16 693. Investigation of some sorption processes on a tantalum getter in an atmosphere of carbon monoxide. (Poland) Conditions of sorption of residual gases on tantalum are investigated. A dependence of the carbon monoxide partial pressure on the temperature of the tantalum filament is found. Optimum carbon monoxide sorption on tantalum occurs at 125O’C, while at 85O’C sorption does not take place. The maximum desorption is observed at 16OO’C and above this temperature sorption again increases. Causes of this behaviour are not explained. A Pietraniec and P Chocisnowski, Zesz Narrk P C’zcst, No 66, I97 I, I 5-20 (in Pdish). 16 : 18 of electronic properties of surface after adsorption of various gases by the method of exoelectron emission. (USSR) Exoelectron emission from surface of ;J-aluminium oxide at 300 K IS investigated before and after adsorption of H,, CO, and N,O. it is shown that adsorption of H, results in enhancement of exoemission, while adsorption of CO, and N,O considerably reduces exoelectron emission. Experimental results are discussed. D 1 Baazov et al, Izv AN SSSR SW I?‘,-, 35 (2). 1971, 361-365 (i/f RWWiU,!). 694. Investigation
240
16 : 18 695. Mechanism of action of oxygen on properties of Ag-0-Cs photocathode. (USSR) Variations in electrical conductivity, thermionic and photoelectron emission, electron affinity and thermionic work function of the Ag-0-Cs photocathode are studied at different stages of its sensitization by oxygen. The mechanism of oxygen action on these parameters is considered. M T Pakhomov and A E Melamid, Iz,, AN SSSR SW Fiz, 35 (2). 197 I, 307.-3 I4 (i/r Russicul). 16 : 37 696. Arrangement for investigation of the diffusion coefficient, permea(USSR) tion and solubility of hydrogen and deuterium in metals. A vacuum system with base pressure of 10e5 torr for simultaneous measurement of the diffusion coefficient and permeation of hydrogen in metals over the broad temperature range of 200 to 900°C is described. Three McLeod gauges are used in the measuring sections. V A Goltsov et al, Zavorlsk Lab, 37 (6), 1971, 740-741 (in Russian).
18. GASEOUS
ELECTRONICS
I8 697. Adsorption-emission characteristics of films of rare earth metals (USSR) on faces of single crystal tungsten. Using sealed field emission and emission spherical microscopes, adsorption of Y, La, Cd, Ce and Eu on faces of single crystal tungsten is investigated in vacuum at 1 s lo-$ torr. Work function and heat of evaporation of adsorbed films are determined. It is found that the most active system is La on (I 11)and (116) W faces. A V Garnov et al, Iz\, AN SSSR Ser Fiz, 35 (2), 1971, 341-344 (in Rlr.wiu/r). I8 698. Threshold theory of influence of adsorption on field and photoelectron emission. (USSR) Changes in the dependence of the emission current on external electric field and in the energy distribution of emitted electrons caused by adsorption on surface of emitter are considered. Influence of adsorption on field and photoelectron emission is studied with respect to the discrete structure of the adsorbed layer. A M Brodskiy et al, Izv AN SSSR Ser Fiz, 35 (2), 1971, 366-372 (in Russian). 18 699. Light-stimulated secondary electron emission and investigation of (USSR) adsorption processes by the photoelectron emission method. The simultaneous action of illumination and electron bombardment on polycrystalline silver is investigated in a glass device of the spherical capacitor type at a residual gas pressure of lo-” torr. It is found that the resulting emission current is smaller than the sum of the photocurrent and the secondary emission current measured separately. Adsorption processes are studied with the aid of a highvacuum photo-emission microscope with magnification of 75 to 150 and residual gas pressure of IO-* torr. The process of deposition of BaO active material on MO metallic substrate was observed. It is found that the initial stage of adsorption takes place on irregularities of substrate surface. Variations in image contrast with further evaporation of BaO on MO, are observed. I Buribaev and B B Shishkin, Izv AN SSSR Ser Fiz, 35 (2), I97 1, 323% 326 (a Rmiun). I8 700. Influence of radiation and dimensions of samples on breakdown characteristics on the surface of an epoxy compound in vacuum. (USSR) Analysis of results of measurements and investigations of sample surfaces after vacuum breakdown show that non-irradiated epoxy compound insulators are resistant against cracking. After multiple flashovers with discharge currents of 0.5 to 1 A no traces of disturbance were observed on epoxy insulators. The voltage of flashover remained high after many flashovers on surface of the samples. Breakdown characteristics of epoxy surfaces in vacuum are very good. The electrical insulation properties of epoxy surfaces are preserved at absorption of doses up to 10” rad. Epoxy compound is recommended as an insulator material suitable for application in ~aciiiim systems. S D Isdmukhamedov et al, DohI Akutl Nurrk Uzbec SSR, No 6, 1971, 30~32 (i/r R~~s.sim).