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Surface behavior under ion bombardment in a fusion device
Classified abstracts 3340-3346 base films vapour-quenched onto glass substrates. A similar technique has already been used for producing Al-type overlays of S, Ge, Sn, Se and Te. On annealing cyclically at increasing temperatures, a critical temperature is reached at which the overlay breaks because of the transformation of the Al-type modification to the usual crystal structure. Both the density and the superconducting transition temperature of the overlay depend on the base-film material and increase, for each element, with decreasing base-film lattice constant. The density is larger than the ordinary, but smaller than would be expected for a perfect pseudomorph or an ideal close-packed atom arrangement. The superconducting transition temperature is higher the thinner the overlay and the lower the annealing temperature. A comparison with previous results shows that the superconducting transition temperature of the Al-type overlays is higher than both that of films with normal crystal1 structure quench-condensed directly on glass substrates and that of samples subjected to high pressures. (Italy) CRcaIe, Vacuum, 27 (l), 1977,3-6.
3 1. SPUTTERING 21 3340. The roughness parameters of glass films. (GB) Thin films of Comina 7059 alass were deoosited onto soda lime nlass substrates by rf sputtering. Profiles of the surfaces of the films-and substrates were obtained using a Tallystep and these were digitally processed to yield the rms roughness amplitude of approximately 6 nm, the autocorrelation length of about 2.9 pm and also the rms roughness angle of 0.3”. There was normally little diierence between the roughness of the film and substrate. However it was found that the surface roughness of the films grown with the sputtering electrode earthing shield exposed or else when a metal mask was placed on the substrate, were substantially rougher than films sputtered whilst the target covered the earthing shield and when a glass mask was used. It was concluded that the large roughness nodules were largely attributable to sputtered metallic particles forming preferential nucleation sites around which rapid growth occurred. Surface roughness profiles of Pilkington Float Glass were also obtained; the rms amplitude was 0.8 nm and the cqrrelation length was 26.6 pm. The extreme smoothness of this glass indicates that it might be useful as a substrate for rf sputtered glass optical waveguides. A silicon slice as prepared for the manufacture of integrated circuits was also found to be very smooth. D J Walter and J Houghton, Vucuum, 27 (l), 1977,7-10.
32. EVACUATION
AND SEALING
32 3341. Barium, strontium and calcium as getters in electron tubes. (USA) Strontium and calcium getters have possible use replacing barium as gas sorbers in color picture tubes and other electron tubes. Stable getters were made of a calcium-aluminium or strontium-aluminium alloy, which was powdered, mixed with nickel powder and pressed into a ring-shaped channel of stainless steel. After exhaust pumping and tip-off of the picture tube, the getter was heated to form a gassorbing film of strontium or calcium, which was deposited by evaporation onto the internal surfaces of the picture tube.. Strontium and calcium getters were evaluated and compared to barium getters in color picture tubes by the oxygen sorbtion test, which determined the maximum oxygen quantity that can be adsorbed by the film without damage to the tube’s oxide cathode. When flashed in 25 in. color tubes, barium and strontium showed the same oxygen capacity both initially and after 11 and 25 weeks of the life test. When flashed in tubes of smaller size and surface area, strontium showed lower oxygen capacity than barium, a result indicated slower bulk diffusion of oxygen through thick films of strontium oxide than through barium oxide. Calcium showed satisfactory gettering speed allowing normal tube operation out to 25 weeks of life test; however its gettering capacity was lower, being about l/4 that of barium and indicating even slower diffusion of oxygen in calcium oxide than in strontium oxide. J C Turnbull, J Vuc Sci Technol, 14 (I), 1977, 636-639. 92
33. NUCLEONICS 33 3342. Special aspects of vacuum systems for fusion experiments. (USA) The design of vacuum systems for fusion experiments is governed by the geometry of the apparatus causing limited access to the vacuum vessel. The vessel has to sustain a variety of forces exerted by the magnetic field not encountered in other vacuum applications. Further problems arise from the plasma-wall interaction, from neutral injection and from high, energetic particle fluxes in divertor chambers. European answers to these tasks will be reviewed from the outline of the experiments ASDEX, TEXTOR and JET. W Heiland, J Vat Sci Technol, 14 (1). 1977, 576-581. 33 3343. Pumping and vacuum requirements for the magaetic fusion energy program. (USA) The Division of Magnetic-Fusion Energy (DMFE) in the US ERDA is responsible for the development of the necessary technology for the magnetically confined fusion energy source. The vacuum technology requirements will be met to assure a demonstration power reactor by the end of this century. The objective of this paper is to present an overview of the pumping and vacuum requirements for future technology development. The fusion-reactor vacuum subsystems will be discussed with the identification of general operating requirements needed to achieve the desired reacting fusion plasma conditions. A program will be outlined for the development of vacuum technology necessary to support the evolving fusion reactor and auxiliary system designs. H S Cullingford and J W Real, J Vat Sci Tech&, 14 (1). 1977, 567569. 33 3344. Some fusion-device materials research st Lawrence Livermore Laboratory. (USA) Much of the fusion materials research at Lawrence Livermore Laboratory (LLL) centers around the high-intensity d-t 14 MeV neutron source. Considerable effort is being expended in determining the characteristics of bulk damage resulting from 14 MeV neutrons. In addition, surface sputtering by 14 MeV neutrons is being investigated. Surface-sputtering measurements were made on two different types of niobium targets-an optically polished sample with a rough micromorphology and a chemically etched sample with a smooth microsurface. Both targets resulted in atomic sputter yields of (1-2)x 10ms sputter atoms per neutron, in good agreement with calculations based on linear Boltxmann transport theory. However, chunk emission was also observed from the rough target; many chunks the order of 2 pm in size were seen, resulting in a total sputter yield of about 1 x 10s4. Such a sputter yield should not be particularly harmful to a fusion reactor. R G Meisenheimer, J Vuc Sci Technol, 14 (1). 1977,560-W. 33 3345. Reduction of surface erosion in fusion reactors. (USA) Some of the major processes leading to surface erosion in fusion reactors are reviewed briefly, including blistering by implanted gas, sputtering by ions, atoms and neutrons and vaporization by local heating. Surface erosion affects the structural integrity and limits the lifetime of reactor components exposed to plasma radiation. In addition, some of the processes leading to surface erosion also cause the release of plasma contaminants. Methods proposed to IT&X surface erosion have included control of surface temperature, selection of materials with a favorable microstructure, chemical and mechanical treatment of surfaces and employment of protective surface coatings, wall liners and divertors. The advantages and disadvantages of some of these -methods are discussed. T D Rossing et al, J Vat Sci Technof, 14 (l), 1977,550-558. 33 3346. Surface behavior under ion bombardment in a f&ion device. (USA) First wall, divertors and other components of the vacuum chamber of a fusion reactor will be submitted to ion bombardment from the thermonuclear plasma. The effects of this bombardment on the materials must be known in order to foresee and correct any major problem. Particular attention must be given to the erosion of the materials. The major mechanisms responsible for wall erosion in a fusion device, namely sputtering, blistering, and evaporation, are revised. The erosion rate due to sputtering is reported for different
Classified abstracts 3347-3355 materials and bombarding energies. A review of the effects of blistering on surface morphology and erosion is made as a function of energy, ion dose and temperature of the material. The evolution of surface temperature under various bombardment power is given and correlated to probable evaporation rates. The relative importance of these different phenomena is assessed. (Canada) J G Martel et al, J Vuc Sci Technol, 14 (1). 1977, 543-549. 33 3347. Thermal desorption measurements of helium ion-implanted erbium tritide. (USA) In an attempt to simulate aging tritides, samples of Er3H1.* were implanted with 4He shortly after being loaded with tritium. Two implant schedules were used which were designed to give uniform imolants of 0.13 4He/Er and 0.20 4He/Er. After aoproximately 150 days, the 3He from the decayed tritium and the %k were de&bed by thermal ramping from room temperature to 1200 K. The concentration of 3He before desorption was 0.044 “He/Er. The results are compared with similar experiments performed on aged erbium tritides in which the 3He/Er was 20.31. In the case of the ionimplanted samples, more than 99% of the desorbed helium is contained in a peak at 1130 K, whereas for the aged samples, two desorption peaks are seen at 400 and I100 K. W J Rass, J Vat Sci Tech&, 14 (l), 1977,518-522. 33 3348. Helium detrappbtg and release from metal tritides. (USA) Interstitial helium /i-decay products remain trapped in metal tritides until a critical threshold concentration is attained. This concentration appears to be independent of host metal-atom species for a significant number of CaF,-structure ditritides. The role of strains in these materials is discussed, and a strain model is presented which is consistent with known release behavior as well as X-ray latticeparameter studies. This model predicts that in many cases the threshold helium concentration is simply related to the critical concentration for (site) percolation of interstitial helium atoms. An experimental test of this model, which I have proposed and which is in preparation, is discussed. W J Camp, J Vuc Sci Technol, 14 (l), 1977,514517. 33 3349. Use of nonevaporable getter pumps in experimental fusion reactors. (USA) Auxiliary pumping means for nuclear fusion experiments are foreseen inside the plasma chamber or in separated chambers (divertors), which must develop high pumping speed and capacity for H2 and its isotopes as well as for impurities and which must also meet special requirements regarding materials, space availability and operating conditions. The fundamental properties of SORB-AC cartridges seem to make them particularly suitable for such pumping needs in fusion machines. A practical example is described for the case of a divertor section of such a machine. The pumping efficiency has been theoretically investigated using a Monte Carlo technique which allows the investigation of the influence of various geometrical and physical parameters. (Italy) M Borghi and B Ferrario, J Vat Sci Technol, 14 (l), 1977, 570-574.
35. PROCESSING
OF MATERIALS
35 3350. Freeze drying of pharmaceuticals. (USA) The desired characteristics of a freeze-dried pharmaceutical dosage form include (1) an intact cake occupying same shape and size as the original frozen mass. (2) sufficient strength to prevent cracking, powdering. or collapse, (3) uniform color and consistency and (4) rapid reconstitution. These characteristics can be achieved by proper formulation of the product and by employing optimum freezedrying cycles. The development of a suitable formulation and a freeze-dry cycle requires knowledge of some basic properties as (1) eutectic temperature, (2) temperature effect on solubility, (3) degree of supercooling, (4) heat transfer properties of the freeze-dryer shelves, metal trays, glass vials, and the frozen product and (5) equipment design and equipment capability. Through the determination of eutectic temperature and knowledge of the temperature effect on solubility of a drug and the thermal conductivity of the frozen mass it is possible to optimize cycles and cut costs. Utilizing resistivity measurements to determine eutectic temperature and
supercooling properties of several pharmaceuticals, batch sizes were increased and the overall time for freeze-drying was reduced. P P DeLuca, J Vat Sci Technol, 14 (l), 1977,620-629. 35 3351. Metal losses of Re, W, MO, Ta and Nb by oxide evaporation in low-pressure oxygen-containing atmospheres. (Germany) During annealing of the hiah-melting metals Re. W. MO. Ta and Nb in oxygen, air and water vapour at low pressures and high temperatures, the metal evaporation rates are markedly increased due to the formation of volatile oxides. The complex pressure and temperature dependence of the metal loss observed is consistent with results of mass spectrometric investigations obtained by other authors. The gravimetrically determined weight losses and recession rates, respectively, are given for the following temperature and pressure ranges : Re -OO,,air, HJO: 11QO-2300°C,4~ lo-“-4Pa; W - 02, air, HtO: 1400-24OO”C, 1.3 x lo-‘-O.67 Pa; MO- 02, air, HzO: 1400-23OO”C, 1.3 x lo-‘-O.67 Pa; Ta - 02, HzO: 1950-25OO”C, 1.3 x 10-4-0.13 Pa; Nb-Oz,HzO: 1900-22OO”C, 1.3 x 10m4-1.3 x 10m2 Pa. H Jehn, Vakuum-Tech, 26 (2) 1977,51-57. (in German)
36. VACUUM
INSTRUMENTATION
FOR SURFACE STUDIES 36 energy loss spectra of the system Cu(311)CO, Xe.
3352. Electron (Germany) The electron energy loss spectrum of a clean Cu(311) surface has been studied by reflected electrons using primary energies between 30 and 300 eV. The losses obtained are compared with literature values. LOSS spectra with adsorbed CO and Xe are also reported. Some assignments of the loss mechanisms have been attempted. H Papp, Vukuum-Tech, 26 (2), 1977,34-39. (in German) 36 3353. The range of doubly charged boron ions. (GB) The ranges of singly and doubly charged boron ions of the same energy implanted into silicon and silicon dioxide have been measured by three different methods. There is found to be no dependence of the boron ion range upon its charge state. The ranges measured are compared with others obtained experimentally and also with theoretically predicted values. N G Blamires and B J Smith, J Phys D: Appf Phys, 10 (5). 1977,799804. 36 3354. Angle-resolved synchrotron photoemission studies of clean and chemisorbed surfaces. (USA) Ultraviolet photoemission spectroscopy (UPS) has been developed into an important tool in the study of solid surfaces and adsorbed over-layers. Until recently, several important parameters in the photoemission process have been, at best, only imperfectly under the control of the experimenter. These are (1) photon energy, (2) optical polarization and (3) momentum of the emitted electrons. Such limitations have concealed much information implicit in the flux of photoemitted electrons. Angle-resolved UPS, combined with the continuum and polarization properties of synchrotron radiation, lifts these limitations to a large degree and provides experimental evidence for three- and two-dimensional band structure, surface states and electronic and geometric properties of adsorbed species. We show some results of such experiments for clean and chemisorbed W. The data show a variable degree of complexity and, in general, may be analyzed only in the context of specific calculations. G J Lapeyre et al, J Voc Sci Technol, 14 (l), 1977.384-390. 36 3355. ESCA studies of naturally passivated metal foils. (USA) X-ray photoelectron spectroscopy (ESCA) has been employed to examine several elemental metal foils which were simultaneously allowed to develop natural passivation (oxidation) layers. The metals considered included representative transition metals and also several Group III and IV elements. Sputter etching was employed to establish approximate depth profiles. Highly reproducible results for the individual components made it possible to identify all of the major constituents. These results have yielded new information in the metallurgy and surface science of these systems. In order to properly study these systems, we have found it necessary to use an electron 93
3 1. SPUTTERING 21 3340. The roughness parameters of glass films. (GB) Thin films of Comina 7059 alass were deoosited onto soda lime nlass substrates by rf sputtering. Profiles of the surfaces of the films-and substrates were obtained using a Tallystep and these were digitally processed to yield the rms roughness amplitude of approximately 6 nm, the autocorrelation length of about 2.9 pm and also the rms roughness angle of 0.3”. There was normally little diierence between the roughness of the film and substrate. However it was found that the surface roughness of the films grown with the sputtering electrode earthing shield exposed or else when a metal mask was placed on the substrate, were substantially rougher than films sputtered whilst the target covered the earthing shield and when a glass mask was used. It was concluded that the large roughness nodules were largely attributable to sputtered metallic particles forming preferential nucleation sites around which rapid growth occurred. Surface roughness profiles of Pilkington Float Glass were also obtained; the rms amplitude was 0.8 nm and the cqrrelation length was 26.6 pm. The extreme smoothness of this glass indicates that it might be useful as a substrate for rf sputtered glass optical waveguides. A silicon slice as prepared for the manufacture of integrated circuits was also found to be very smooth. D J Walter and J Houghton, Vucuum, 27 (l), 1977,7-10.
32. EVACUATION
AND SEALING
32 3341. Barium, strontium and calcium as getters in electron tubes. (USA) Strontium and calcium getters have possible use replacing barium as gas sorbers in color picture tubes and other electron tubes. Stable getters were made of a calcium-aluminium or strontium-aluminium alloy, which was powdered, mixed with nickel powder and pressed into a ring-shaped channel of stainless steel. After exhaust pumping and tip-off of the picture tube, the getter was heated to form a gassorbing film of strontium or calcium, which was deposited by evaporation onto the internal surfaces of the picture tube.. Strontium and calcium getters were evaluated and compared to barium getters in color picture tubes by the oxygen sorbtion test, which determined the maximum oxygen quantity that can be adsorbed by the film without damage to the tube’s oxide cathode. When flashed in 25 in. color tubes, barium and strontium showed the same oxygen capacity both initially and after 11 and 25 weeks of the life test. When flashed in tubes of smaller size and surface area, strontium showed lower oxygen capacity than barium, a result indicated slower bulk diffusion of oxygen through thick films of strontium oxide than through barium oxide. Calcium showed satisfactory gettering speed allowing normal tube operation out to 25 weeks of life test; however its gettering capacity was lower, being about l/4 that of barium and indicating even slower diffusion of oxygen in calcium oxide than in strontium oxide. J C Turnbull, J Vuc Sci Technol, 14 (I), 1977, 636-639. 92
33. NUCLEONICS 33 3342. Special aspects of vacuum systems for fusion experiments. (USA) The design of vacuum systems for fusion experiments is governed by the geometry of the apparatus causing limited access to the vacuum vessel. The vessel has to sustain a variety of forces exerted by the magnetic field not encountered in other vacuum applications. Further problems arise from the plasma-wall interaction, from neutral injection and from high, energetic particle fluxes in divertor chambers. European answers to these tasks will be reviewed from the outline of the experiments ASDEX, TEXTOR and JET. W Heiland, J Vat Sci Technol, 14 (1). 1977, 576-581. 33 3343. Pumping and vacuum requirements for the magaetic fusion energy program. (USA) The Division of Magnetic-Fusion Energy (DMFE) in the US ERDA is responsible for the development of the necessary technology for the magnetically confined fusion energy source. The vacuum technology requirements will be met to assure a demonstration power reactor by the end of this century. The objective of this paper is to present an overview of the pumping and vacuum requirements for future technology development. The fusion-reactor vacuum subsystems will be discussed with the identification of general operating requirements needed to achieve the desired reacting fusion plasma conditions. A program will be outlined for the development of vacuum technology necessary to support the evolving fusion reactor and auxiliary system designs. H S Cullingford and J W Real, J Vat Sci Tech&, 14 (1). 1977, 567569. 33 3344. Some fusion-device materials research st Lawrence Livermore Laboratory. (USA) Much of the fusion materials research at Lawrence Livermore Laboratory (LLL) centers around the high-intensity d-t 14 MeV neutron source. Considerable effort is being expended in determining the characteristics of bulk damage resulting from 14 MeV neutrons. In addition, surface sputtering by 14 MeV neutrons is being investigated. Surface-sputtering measurements were made on two different types of niobium targets-an optically polished sample with a rough micromorphology and a chemically etched sample with a smooth microsurface. Both targets resulted in atomic sputter yields of (1-2)x 10ms sputter atoms per neutron, in good agreement with calculations based on linear Boltxmann transport theory. However, chunk emission was also observed from the rough target; many chunks the order of 2 pm in size were seen, resulting in a total sputter yield of about 1 x 10s4. Such a sputter yield should not be particularly harmful to a fusion reactor. R G Meisenheimer, J Vuc Sci Technol, 14 (1). 1977,560-W. 33 3345. Reduction of surface erosion in fusion reactors. (USA) Some of the major processes leading to surface erosion in fusion reactors are reviewed briefly, including blistering by implanted gas, sputtering by ions, atoms and neutrons and vaporization by local heating. Surface erosion affects the structural integrity and limits the lifetime of reactor components exposed to plasma radiation. In addition, some of the processes leading to surface erosion also cause the release of plasma contaminants. Methods proposed to IT&X surface erosion have included control of surface temperature, selection of materials with a favorable microstructure, chemical and mechanical treatment of surfaces and employment of protective surface coatings, wall liners and divertors. The advantages and disadvantages of some of these -methods are discussed. T D Rossing et al, J Vat Sci Technof, 14 (l), 1977,550-558. 33 3346. Surface behavior under ion bombardment in a f&ion device. (USA) First wall, divertors and other components of the vacuum chamber of a fusion reactor will be submitted to ion bombardment from the thermonuclear plasma. The effects of this bombardment on the materials must be known in order to foresee and correct any major problem. Particular attention must be given to the erosion of the materials. The major mechanisms responsible for wall erosion in a fusion device, namely sputtering, blistering, and evaporation, are revised. The erosion rate due to sputtering is reported for different
Classified abstracts 3347-3355 materials and bombarding energies. A review of the effects of blistering on surface morphology and erosion is made as a function of energy, ion dose and temperature of the material. The evolution of surface temperature under various bombardment power is given and correlated to probable evaporation rates. The relative importance of these different phenomena is assessed. (Canada) J G Martel et al, J Vuc Sci Technol, 14 (1). 1977, 543-549. 33 3347. Thermal desorption measurements of helium ion-implanted erbium tritide. (USA) In an attempt to simulate aging tritides, samples of Er3H1.* were implanted with 4He shortly after being loaded with tritium. Two implant schedules were used which were designed to give uniform imolants of 0.13 4He/Er and 0.20 4He/Er. After aoproximately 150 days, the 3He from the decayed tritium and the %k were de&bed by thermal ramping from room temperature to 1200 K. The concentration of 3He before desorption was 0.044 “He/Er. The results are compared with similar experiments performed on aged erbium tritides in which the 3He/Er was 20.31. In the case of the ionimplanted samples, more than 99% of the desorbed helium is contained in a peak at 1130 K, whereas for the aged samples, two desorption peaks are seen at 400 and I100 K. W J Rass, J Vat Sci Tech&, 14 (l), 1977,518-522. 33 3348. Helium detrappbtg and release from metal tritides. (USA) Interstitial helium /i-decay products remain trapped in metal tritides until a critical threshold concentration is attained. This concentration appears to be independent of host metal-atom species for a significant number of CaF,-structure ditritides. The role of strains in these materials is discussed, and a strain model is presented which is consistent with known release behavior as well as X-ray latticeparameter studies. This model predicts that in many cases the threshold helium concentration is simply related to the critical concentration for (site) percolation of interstitial helium atoms. An experimental test of this model, which I have proposed and which is in preparation, is discussed. W J Camp, J Vuc Sci Technol, 14 (l), 1977,514517. 33 3349. Use of nonevaporable getter pumps in experimental fusion reactors. (USA) Auxiliary pumping means for nuclear fusion experiments are foreseen inside the plasma chamber or in separated chambers (divertors), which must develop high pumping speed and capacity for H2 and its isotopes as well as for impurities and which must also meet special requirements regarding materials, space availability and operating conditions. The fundamental properties of SORB-AC cartridges seem to make them particularly suitable for such pumping needs in fusion machines. A practical example is described for the case of a divertor section of such a machine. The pumping efficiency has been theoretically investigated using a Monte Carlo technique which allows the investigation of the influence of various geometrical and physical parameters. (Italy) M Borghi and B Ferrario, J Vat Sci Technol, 14 (l), 1977, 570-574.
35. PROCESSING
OF MATERIALS
35 3350. Freeze drying of pharmaceuticals. (USA) The desired characteristics of a freeze-dried pharmaceutical dosage form include (1) an intact cake occupying same shape and size as the original frozen mass. (2) sufficient strength to prevent cracking, powdering. or collapse, (3) uniform color and consistency and (4) rapid reconstitution. These characteristics can be achieved by proper formulation of the product and by employing optimum freezedrying cycles. The development of a suitable formulation and a freeze-dry cycle requires knowledge of some basic properties as (1) eutectic temperature, (2) temperature effect on solubility, (3) degree of supercooling, (4) heat transfer properties of the freeze-dryer shelves, metal trays, glass vials, and the frozen product and (5) equipment design and equipment capability. Through the determination of eutectic temperature and knowledge of the temperature effect on solubility of a drug and the thermal conductivity of the frozen mass it is possible to optimize cycles and cut costs. Utilizing resistivity measurements to determine eutectic temperature and
supercooling properties of several pharmaceuticals, batch sizes were increased and the overall time for freeze-drying was reduced. P P DeLuca, J Vat Sci Technol, 14 (l), 1977,620-629. 35 3351. Metal losses of Re, W, MO, Ta and Nb by oxide evaporation in low-pressure oxygen-containing atmospheres. (Germany) During annealing of the hiah-melting metals Re. W. MO. Ta and Nb in oxygen, air and water vapour at low pressures and high temperatures, the metal evaporation rates are markedly increased due to the formation of volatile oxides. The complex pressure and temperature dependence of the metal loss observed is consistent with results of mass spectrometric investigations obtained by other authors. The gravimetrically determined weight losses and recession rates, respectively, are given for the following temperature and pressure ranges : Re -OO,,air, HJO: 11QO-2300°C,4~ lo-“-4Pa; W - 02, air, HtO: 1400-24OO”C, 1.3 x lo-‘-O.67 Pa; MO- 02, air, HzO: 1400-23OO”C, 1.3 x lo-‘-O.67 Pa; Ta - 02, HzO: 1950-25OO”C, 1.3 x 10-4-0.13 Pa; Nb-Oz,HzO: 1900-22OO”C, 1.3 x 10m4-1.3 x 10m2 Pa. H Jehn, Vakuum-Tech, 26 (2) 1977,51-57. (in German)
36. VACUUM
INSTRUMENTATION
FOR SURFACE STUDIES 36 energy loss spectra of the system Cu(311)CO, Xe.
3352. Electron (Germany) The electron energy loss spectrum of a clean Cu(311) surface has been studied by reflected electrons using primary energies between 30 and 300 eV. The losses obtained are compared with literature values. LOSS spectra with adsorbed CO and Xe are also reported. Some assignments of the loss mechanisms have been attempted. H Papp, Vukuum-Tech, 26 (2), 1977,34-39. (in German) 36 3353. The range of doubly charged boron ions. (GB) The ranges of singly and doubly charged boron ions of the same energy implanted into silicon and silicon dioxide have been measured by three different methods. There is found to be no dependence of the boron ion range upon its charge state. The ranges measured are compared with others obtained experimentally and also with theoretically predicted values. N G Blamires and B J Smith, J Phys D: Appf Phys, 10 (5). 1977,799804. 36 3354. Angle-resolved synchrotron photoemission studies of clean and chemisorbed surfaces. (USA) Ultraviolet photoemission spectroscopy (UPS) has been developed into an important tool in the study of solid surfaces and adsorbed over-layers. Until recently, several important parameters in the photoemission process have been, at best, only imperfectly under the control of the experimenter. These are (1) photon energy, (2) optical polarization and (3) momentum of the emitted electrons. Such limitations have concealed much information implicit in the flux of photoemitted electrons. Angle-resolved UPS, combined with the continuum and polarization properties of synchrotron radiation, lifts these limitations to a large degree and provides experimental evidence for three- and two-dimensional band structure, surface states and electronic and geometric properties of adsorbed species. We show some results of such experiments for clean and chemisorbed W. The data show a variable degree of complexity and, in general, may be analyzed only in the context of specific calculations. G J Lapeyre et al, J Voc Sci Technol, 14 (l), 1977.384-390. 36 3355. ESCA studies of naturally passivated metal foils. (USA) X-ray photoelectron spectroscopy (ESCA) has been employed to examine several elemental metal foils which were simultaneously allowed to develop natural passivation (oxidation) layers. The metals considered included representative transition metals and also several Group III and IV elements. Sputter etching was employed to establish approximate depth profiles. Highly reproducible results for the individual components made it possible to identify all of the major constituents. These results have yielded new information in the metallurgy and surface science of these systems. In order to properly study these systems, we have found it necessary to use an electron 93