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Techniques of obtaining high-purity surfaces
Classified Classified
abstracts
abstracts
1323440
1323-1334 on this page
Editor’s note The label immediately following the title of each item denotes country or origin of publication, and that at the end of each abstract indicates country of origin of work (where known).
I. General vacuum 10. VACUUM
SCIENCE
science
and engineering
AND TECHNOLOGY 10
1323. The 4th International
: 64
Vacuum Congress in Manchester.
(Czechoslovakia) This brief review is given on devices exhibited and the papers presented Z Piskacek, Jemna Mech Opt, 13 (7), July 1968, cover (in Czech). 10 (USA) 1324. Where do standards stand?
: 61
Four experts (D G Bill, B B Dayton, D P Johnson and A Nerken) discuss standards in the field of vacuum technology. The evolution of vacuum standards in USA is discussed with reference to the international standardization activities. The activities in this field are reviewed and the problems encountered are critically discussed. C J Mosbacher, ResjDevelop, 19 (4), 1968, 48-56. 12. MEASUREMENT
OF LOW
PRESSURE 12
1325. Production and measurement
of vacuum. Part 2.
(USSR) This part of the handbook of the Leningrad Electrotechnical Institute deals with statistical viscosity, thermal and thermomolecular gauges. 0 V Sokolov, book publd by Uchebnye Posobie, Leningrad, 138 pages, price 1.50 Rb (in Russian). 14. KINETIC
THEORY
OF GASES
14 1326. Frictional forces and collision frequencies between moving ion and neutral gases. (USA)
Two different terms are used in literature for the frictional force between moving ion and neutral gases. It is shown how the corresponding collision frequencies have to be defined in order to keep both terms valid. An expression is derived for the momentum transfer collision frequency between ions and neutral particles as a function of temperature and the relative flow velocity. P Stubbe, Rep NASA-TM-X-63079, Nov 1967, 44 pages (Sci Tech Aerospace 16. GASES
Reps, 6 (6), 834, N68-15348). AND
SOLIDS 16
(USSR) 1327. On the nature of chemisorption. A theory of chemisorption based on the idea of energetic
nets is presented. The energy of molecules on peaks of the energetic barrier is not emitted as heat when the barrier is overcome but a part of the energy may be given to surrounding molecules to overcome the barrier. A similar process takes place during desorption. The chemisorbed layer grows on “seeds” of molecules adsorbed by any type of sorption. G D Sakharov, Dokl Akad Nauk SSSR, 180 (l), 1st May 1968, 154-157 (in Russian). 1328. On the nature of the reversible and irreversible sorption on semiconductors. (USSR)
16 forms of chemi-
Chemisorption of Oz on TiOe was measured by electron emission. At support temperatures of 20 to 150°C the chemisorption is irreversible but at temperatures of 200 to 300°C the sorption is particularly reversible. E N Fignrovskaya and F F Vol’kenshteny, Dokl Akad Nauk SSSR, 180 (2), 11th May 1968, 408-411 (in Russian). 1329. Field emission microscope a high electric field. (USSR)
16 : 18 study of niobium surface diffusion in
From investigations of emission patterns in a Mueller Microscope the profile of a heated niobium tip was examined and changes caused
by migration of surface atoms in a high electric field were observed. The energy of activation of surface diffusion was found to be 2.37 eV at 1500°K. During the experiment the radius of the niobium tip was reduced from 4900 A to 3300 A, by the migration. G A Odishariya, Fiz Tverd Tela, 10 (5), May 1968, 1425-1432 (in Russian). 16 1330. Techniques of obtaining high-purity
surfaces.
(Poland) The surface cleaning of metallic and semiconductor specimens is reviewed including heating, electron and ion bombardment under high vacuum or obtaining clean surfaces by cleaving under UHV. The influence of these methods on the photoemission properties of the surfaces is discussed. J Wojas, Postepy Fir, 19 (3), 1968, 291-307 (in Polish). 1331. Heterogeneity of adsorptive bond of carbon monoxide (USA) surfaces of pure iron and nickel films.
16 : 30 on the
Thin nickel and iron films, obtained by ultrahigh vacuum deposition at 77°K and subsequently tempered at 333°K were exposed to isotopic marked carbon monoxide flow. Mass spectrographic measurements on carbon monoxide absorption and resistance changes of films during molecular adsorption showed that: (1) carbon monoxide was stationary adsorbed to nickel at 77°K and to iron almost stationary; (2) carbon monoxide molecules adsorbed to the surface at differing stabilities; (3) molecular adsorption on iron films showed fluctuating exchange tendencies; (4) differences in molecular surface bonding were caused by the heterogeneity of the film surface, and (5) the (Germany) molecular exchange was a second order reaction. K Fricke, PhD Thesis, Techn Hochschule Hannover, 62 pages German), (Sci Tech Aerospace Reps, 6 (6), 786, N68-15043).
(in
16 1332. On the adsorptive bindmg of carbon monoxide on pure gold iilms. (USA)
Carbon monoxide adsorption on thin gold films, and on glass surfaces was studied by isothermal and electrical resistance measurements in an ultrahigh vacuum environment. Carbon monoxide molecular adsorption onto gold films at 77°K showed enthalpies of 8-9 kcal/Mol at low gas densities and of 4 kcal/Mol at higher gas densities. A temperature increase to 273°K lowered adsorption tendencies markedly concurrent with molecular motion increase. (Germany) E Kramp, Ph D Thesis, Tech Hochschule Hannover, 1966, 157 pages (in German),
(Sci Tech Aerospace
Reps, 6 (6), 786, N68-15203). 16
1333. The reaction of hydrogen on nickel Bhn.
(USA) Calorimetric measurements of hydrogen adsorption on thin nickel films in a high vacuum of 10-l” torr at 77°K to 273°K were used to determine adsorption heat by evaluating the obtained temperaturetime diagrams. Adsorption experiments with the systems nickel/ carbon monoxide/hydrogen and nickel/oxygen/hydrogen showed increased adsorption heat caused by the hydrogen reaction with the already adsorbed gas molecules. (Germany) F J Broecker, PhD Thesis, Tech Hochschule Hannover, 1967,85 pages (in German), /Sci Tech Aerospace
Reps, 6 (6), 786, N68-15214).
17. THERMODYNAMICS 17 : 34 (USA) 1334. Advanced requirements for cryogenic Insulation. Requirements examined in a research programme for advancing the state of technology for prolonged storage of liquid hydrogen in space flights are outlined. D A Gil&d, Rep NASA-TM-X-53670, 1967 Vol 2, l-2 (Sci Tech Aerospace Reps, 6 (5), 756, N68-14652). 573
abstracts
abstracts
1323440
1323-1334 on this page
Editor’s note The label immediately following the title of each item denotes country or origin of publication, and that at the end of each abstract indicates country of origin of work (where known).
I. General vacuum 10. VACUUM
SCIENCE
science
and engineering
AND TECHNOLOGY 10
1323. The 4th International
: 64
Vacuum Congress in Manchester.
(Czechoslovakia) This brief review is given on devices exhibited and the papers presented Z Piskacek, Jemna Mech Opt, 13 (7), July 1968, cover (in Czech). 10 (USA) 1324. Where do standards stand?
: 61
Four experts (D G Bill, B B Dayton, D P Johnson and A Nerken) discuss standards in the field of vacuum technology. The evolution of vacuum standards in USA is discussed with reference to the international standardization activities. The activities in this field are reviewed and the problems encountered are critically discussed. C J Mosbacher, ResjDevelop, 19 (4), 1968, 48-56. 12. MEASUREMENT
OF LOW
PRESSURE 12
1325. Production and measurement
of vacuum. Part 2.
(USSR) This part of the handbook of the Leningrad Electrotechnical Institute deals with statistical viscosity, thermal and thermomolecular gauges. 0 V Sokolov, book publd by Uchebnye Posobie, Leningrad, 138 pages, price 1.50 Rb (in Russian). 14. KINETIC
THEORY
OF GASES
14 1326. Frictional forces and collision frequencies between moving ion and neutral gases. (USA)
Two different terms are used in literature for the frictional force between moving ion and neutral gases. It is shown how the corresponding collision frequencies have to be defined in order to keep both terms valid. An expression is derived for the momentum transfer collision frequency between ions and neutral particles as a function of temperature and the relative flow velocity. P Stubbe, Rep NASA-TM-X-63079, Nov 1967, 44 pages (Sci Tech Aerospace 16. GASES
Reps, 6 (6), 834, N68-15348). AND
SOLIDS 16
(USSR) 1327. On the nature of chemisorption. A theory of chemisorption based on the idea of energetic
nets is presented. The energy of molecules on peaks of the energetic barrier is not emitted as heat when the barrier is overcome but a part of the energy may be given to surrounding molecules to overcome the barrier. A similar process takes place during desorption. The chemisorbed layer grows on “seeds” of molecules adsorbed by any type of sorption. G D Sakharov, Dokl Akad Nauk SSSR, 180 (l), 1st May 1968, 154-157 (in Russian). 1328. On the nature of the reversible and irreversible sorption on semiconductors. (USSR)
16 forms of chemi-
Chemisorption of Oz on TiOe was measured by electron emission. At support temperatures of 20 to 150°C the chemisorption is irreversible but at temperatures of 200 to 300°C the sorption is particularly reversible. E N Fignrovskaya and F F Vol’kenshteny, Dokl Akad Nauk SSSR, 180 (2), 11th May 1968, 408-411 (in Russian). 1329. Field emission microscope a high electric field. (USSR)
16 : 18 study of niobium surface diffusion in
From investigations of emission patterns in a Mueller Microscope the profile of a heated niobium tip was examined and changes caused
by migration of surface atoms in a high electric field were observed. The energy of activation of surface diffusion was found to be 2.37 eV at 1500°K. During the experiment the radius of the niobium tip was reduced from 4900 A to 3300 A, by the migration. G A Odishariya, Fiz Tverd Tela, 10 (5), May 1968, 1425-1432 (in Russian). 16 1330. Techniques of obtaining high-purity
surfaces.
(Poland) The surface cleaning of metallic and semiconductor specimens is reviewed including heating, electron and ion bombardment under high vacuum or obtaining clean surfaces by cleaving under UHV. The influence of these methods on the photoemission properties of the surfaces is discussed. J Wojas, Postepy Fir, 19 (3), 1968, 291-307 (in Polish). 1331. Heterogeneity of adsorptive bond of carbon monoxide (USA) surfaces of pure iron and nickel films.
16 : 30 on the
Thin nickel and iron films, obtained by ultrahigh vacuum deposition at 77°K and subsequently tempered at 333°K were exposed to isotopic marked carbon monoxide flow. Mass spectrographic measurements on carbon monoxide absorption and resistance changes of films during molecular adsorption showed that: (1) carbon monoxide was stationary adsorbed to nickel at 77°K and to iron almost stationary; (2) carbon monoxide molecules adsorbed to the surface at differing stabilities; (3) molecular adsorption on iron films showed fluctuating exchange tendencies; (4) differences in molecular surface bonding were caused by the heterogeneity of the film surface, and (5) the (Germany) molecular exchange was a second order reaction. K Fricke, PhD Thesis, Techn Hochschule Hannover, 62 pages German), (Sci Tech Aerospace Reps, 6 (6), 786, N68-15043).
(in
16 1332. On the adsorptive bindmg of carbon monoxide on pure gold iilms. (USA)
Carbon monoxide adsorption on thin gold films, and on glass surfaces was studied by isothermal and electrical resistance measurements in an ultrahigh vacuum environment. Carbon monoxide molecular adsorption onto gold films at 77°K showed enthalpies of 8-9 kcal/Mol at low gas densities and of 4 kcal/Mol at higher gas densities. A temperature increase to 273°K lowered adsorption tendencies markedly concurrent with molecular motion increase. (Germany) E Kramp, Ph D Thesis, Tech Hochschule Hannover, 1966, 157 pages (in German),
(Sci Tech Aerospace
Reps, 6 (6), 786, N68-15203). 16
1333. The reaction of hydrogen on nickel Bhn.
(USA) Calorimetric measurements of hydrogen adsorption on thin nickel films in a high vacuum of 10-l” torr at 77°K to 273°K were used to determine adsorption heat by evaluating the obtained temperaturetime diagrams. Adsorption experiments with the systems nickel/ carbon monoxide/hydrogen and nickel/oxygen/hydrogen showed increased adsorption heat caused by the hydrogen reaction with the already adsorbed gas molecules. (Germany) F J Broecker, PhD Thesis, Tech Hochschule Hannover, 1967,85 pages (in German), /Sci Tech Aerospace
Reps, 6 (6), 786, N68-15214).
17. THERMODYNAMICS 17 : 34 (USA) 1334. Advanced requirements for cryogenic Insulation. Requirements examined in a research programme for advancing the state of technology for prolonged storage of liquid hydrogen in space flights are outlined. D A Gil&d, Rep NASA-TM-X-53670, 1967 Vol 2, l-2 (Sci Tech Aerospace Reps, 6 (5), 756, N68-14652). 573