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A study of adsorption and diffusion behaviour of hydrogen in palladium alloy systems
Classified abstracts 20-30 surface is that if the surface defects form or does n o t f o r m chemlsorpUon centres. F F Vol'kenshteyn, Electron phenomena m adsorption and catalysis on semwonductors, 49-67, b o o k p u b h s h e d by Mtr, M o s c o w 1969, (in
Russian). 16 20. The nature of a chemisorption bond on semiconductor surface. (USSR) T w o m e c h a n i s m s o f elementary c h e m l s o r p t l o n acting on a semic o n d u c t o r surface are presented. T h e first m e c h a n i s m IS based o n the presence o f localized free valencaes o f the Shockley type or T a m m surface levels n o n - s a t u r a t e d by electrons on the clean surface. T h e chem~sorptlon act h a s a character o f q u a n t u m mechanical interactaon between localized surface levels with unoccupied energy states a n d the electron levels o f chemisorbed a t o m or molecule, a n d the b o n d is f o r m e d between localized surface charges a n d the chemisorbate. If the c h e m l s o r p t , o n b o n d is strong e n o u g h , then the T a m m c h e m i s o r p t i o n state is produced. Th~s b o n d m a y have one-electron or two-electron character depending on the occupation n u m b e r o f the energy level. If localized electrons are absent on t h e clean surface, then the c h e m l s o r b a t e Induces the disturbance in the crystal a n d t h u s a locahzed state is produced a n d a weak one-electron chemasorption b o n d Is formed. However, there is always s o m e quantity o f free electrons on the surface, whJch are transferred f r o m the valence to the conductivity band. This free valencies m a y f o r m a two-electron b o n d wath c h e m , s o r b a t e electrons It is very difficult to predetermine whether the c h e m i s o r b e d state will have cation or a n i o n character. T h e t h e r m a l effect in c h e m l s o r p t l o n is discussed. (Czechoslovakia) M Tomasek and J Koutecky, Electron phenomena in adsorption and catalysts on semiconductors, 71-93, book published by Mtr, M o s c o w 1969 (in Ruswan). 16 21. Physical adsorption of nitrogen gas on the polished surface of 347 stainless steel at very low pressures. (USA) A c o m b i n e d s t u d y o f surface characterization a n d physical adsorption was performed for a material c o m m o n l y used in v a c u u m mstrumentaUon, n a m e l y stainless steel. T h e characterization o f the surface was a c c o m p h s h e d by t o p o g r a p h y a n d chemical c o m p o s . t i o n studies. Following this study, physacal adsorption m e a s u r e m e n t s o f nitrogen gas on p o h s h e d 347 stainless steel u n d e r pressure were made. R A Outlaw, Rep NASA-TN-D-5777; L-6891, April 1970, 50 pages (Set Teth Aerospace Reps, 8 (12), 2157, N70-25256). 16 22. A study of adsorption and diffusion behaviour of hydrogen in palladium alloy systems. (USA) T h e absorption a n d diffusion behavaour of h y d r o g e n in various substitutional a n d interstitial alloys o f palladium was investigated by m e a n s o f electrochemical m e a s u r i n g techmques. It was f o u n d that the addition o f sdver, gold, or lead to the crystal lattice of palladium, alters the a b s o r p t i o n b e h a w o u r by e n h a n c i n g the initial h y d r o g e n solubility a n d by decreasing the solubility at high a m b i e n t hydrogen pressures K D Allard, Rep Vermont Untv, Microfilm No 69-20304, 244 pages (Sci Tech Aerospace Reps, 8 (12), 2158, N70-25291). 18. G A S E O U S E L E C T R O N I C S 18 23. Thermionic emission properties of transition metal monocarbides of IV or V group in the homogeneity region. ( G e r m a n y ) T h e dependence of work function on concentration is m e a s u r e d for titanium, zirconium, m o b m m a n d t a n t a l u m m o n o c a r b i d e s in a h o m o g e n e i t y range. Carbides are prepared by v a c u u m synthesis. T h e r m i o m c properties are Investigated In a n a p p a r a t u s with electron b e a m heating W o r k function is determined by the m e t h o d of saturation current in a t e m p e r a t u r e range o f 1500 to 2100°K. (USSR) V S F o m e a k o et al, Phys Status Sohdt (a), 2 (3), July 1970, K 1 8 1 - K I 8 4
(in German). 18 24. Emission cross sections of N2 in the vacuum ultraviolet by electron impact. T h e electron b e a m e x o t a t l o n s p e c t r u m o f N2 at low pressure (0.120.18 l0 m the wavelength range 1200-2000 ,~ was recorded for m o n o energetac electron impact energies f r o m l0 to 208 eV. T h e spectral features observed included Lyman-Bwge-Hopfield v t h r a h o n a l transih o n s and several atomic nitrogen multaplets produced by dassocaatwe excltataon o f N2. E m i s s i o n cross sectaons were m e a s u r e d a n d s u m m e d 62
to g~ve the cross section for the entire electronic transltaon. T h e a p p a r a t u s used included a n electron source, the electron beam excltataon c h a m b e r a n d a m o n o c h r o m a t o r with photomultapher detector. J M Ajella, J Chem Phys, 53 (3), 1 Aug 1970, 1156-1165 18 25. Investigation of plasma with hot electrons obtained at cyclotron resonance. ( U S S R ) At electron cyclotron resonance heating o f electrons w~th the m d of the wavegulde m e t h o d , h o t electrons wath a t e m p e r a t u r e of 80 keV a n d basic p l a s m a with a temperature o f 100 eV are obtained T h e dascharge is developed at neutral gas pressure of 2 IO ~ torr m the c h a m b e r , a n d for this reason a p l a s m a source ,s used m mare experiments. B I Patrushev et al, Zh tekh Fiz, 40 (7), July 1970, 1363-1370 (m
Ru~Man). 18 26. Measurement of electron energy distribution function in plasma at noise presence. (USSR) T h e electron energy d a s t n b u u o n function at fluctuations presence ,s m e a s u r e d with the and of a probe using a follower for space potential c o m p e n s a t i o n m a d,scharge in a maxture o f a r g o n at a pressure o f 0 6 torr, a n d m e r c u r y v a p o u r at a pressure of 2 5 ~ 10 -3 torr and a discharge current of 100 m A . Yu M K a g a n et al, Zh tekh Ftz, 40 (6), June 1970, 1319-1321 (m
Russian). 18 27. Some peealiarities of ultrahigh frequency oscillations in plasma of short arc discharge in caesium and mercury vapour. (USSR) T h e ultrahigh frequency oscdlatlons of a short caesium a n d m e r c u r y v a p o u r arc dascharge at a low pressure of 10 3 torr are investigated T h e dependence of o s c d l a h o n s on electron current distribution m p l a s m a is found. D Ya Dubko and S M Levitskiy, Zh tekh Ftz, 40 (6), June 1970, 1313
1317 (m Russian). 18 28. Space charge effects in high frequency gas discharge 11. (USSR) It is s h o w n that the course of radao frequency a n d pressure characterastics o f b r e a k d o w n in gases c a n be explained by space charge effects. T h e role of other processes in h,gh frequency discharge imitating m gases at m e d i u m pressure is discussed. G A Anashkin, Zh tekh Ftz, 40 (6), June 1970, 1262-1267 (in Ru.sstan). 18 29. Injection and maintenance of plasma in a closed quadrupole magnetic trap. (USSR) A n experimental apparatus, containing a stainless steel cylinder o f 1 m din. and 1 m length evacuated to pressure o f I 10 ~ torr, two coils for producing a q u a d r u p o l e magneUc field a n d a plasma source, is described. T h e posslbdaty of m a i n t a i n i n g h o t a n d dense plasma is investigated. V P Goneharenko et al, Zh tekh Fiz, 40 (6), June 1970, 1 2 0 6 1 2 1 6 (in
Russian). 18 30. Field emission from G a P . ( G e r m a n y ) Field emission f r o m G a P is investigated. T h e glass emission microscope wath stainless steel flanges for the d e m o u n t a b l e parts as used. T h e v a c u u m system cons,sts o f two m e r c u r y dlffUsaon p u m p s in ser,es with liquid m t r o g e n v a p o u r traps. T h e system pressure after t h o r o u g h b a k e o u t is higher t h a n 10 ~ torr. H y d r o g e n ion etching ~s a d o p t e d for cleaning the tap. T h e use o f l a n t h a n u m h e x a b o n d e coated filament iomzatlon gauge ~s essentml to prevent c o n t a m l n a t a o n o f the tip wath C O a n d HzO molecules which are released by heated tungsten filaments under the action of hydrogen T h e m e t h o d of preparation o f atomacally clean field emission tips on G a P single crystal is descrlbed. T h e G a P samples an the form o f wh,skers having a d m m e t e r of approxamately 50 /~m are m o u n t e d in the macroscope by c e m e n t i n g t h e m to a stainless steel bar. O n e a d v a n t a g e o f using samples m whisker form ts that the extremely high tensile strength of the materml results m very robust tips wh,ch withstand high d e s o r b m g fields without fracturing. T h e tip radii are of the order of 10 -2 cm. T h e currentvoltage plots obtained are f o u n d to be nonlinear, temperature dependent and photosensitive due to the high resistance of the materml. It is deduced that the emission arises from the valence b a n d of the semiconductor, the densaty o f surface states b e m g sufficient to prevent any field penetration. (USA) O H Hughes and P G Bristow, Phys Status Sohdt (a), 2 (3), July 1970, 503-509
Russian). 16 20. The nature of a chemisorption bond on semiconductor surface. (USSR) T w o m e c h a n i s m s o f elementary c h e m l s o r p t l o n acting on a semic o n d u c t o r surface are presented. T h e first m e c h a n i s m IS based o n the presence o f localized free valencaes o f the Shockley type or T a m m surface levels n o n - s a t u r a t e d by electrons on the clean surface. T h e chem~sorptlon act h a s a character o f q u a n t u m mechanical interactaon between localized surface levels with unoccupied energy states a n d the electron levels o f chemisorbed a t o m or molecule, a n d the b o n d is f o r m e d between localized surface charges a n d the chemisorbate. If the c h e m l s o r p t , o n b o n d is strong e n o u g h , then the T a m m c h e m i s o r p t i o n state is produced. Th~s b o n d m a y have one-electron or two-electron character depending on the occupation n u m b e r o f the energy level. If localized electrons are absent on t h e clean surface, then the c h e m l s o r b a t e Induces the disturbance in the crystal a n d t h u s a locahzed state is produced a n d a weak one-electron chemasorption b o n d Is formed. However, there is always s o m e quantity o f free electrons on the surface, whJch are transferred f r o m the valence to the conductivity band. This free valencies m a y f o r m a two-electron b o n d wath c h e m , s o r b a t e electrons It is very difficult to predetermine whether the c h e m i s o r b e d state will have cation or a n i o n character. T h e t h e r m a l effect in c h e m l s o r p t l o n is discussed. (Czechoslovakia) M Tomasek and J Koutecky, Electron phenomena in adsorption and catalysts on semiconductors, 71-93, book published by Mtr, M o s c o w 1969 (in Ruswan). 16 21. Physical adsorption of nitrogen gas on the polished surface of 347 stainless steel at very low pressures. (USA) A c o m b i n e d s t u d y o f surface characterization a n d physical adsorption was performed for a material c o m m o n l y used in v a c u u m mstrumentaUon, n a m e l y stainless steel. T h e characterization o f the surface was a c c o m p h s h e d by t o p o g r a p h y a n d chemical c o m p o s . t i o n studies. Following this study, physacal adsorption m e a s u r e m e n t s o f nitrogen gas on p o h s h e d 347 stainless steel u n d e r pressure were made. R A Outlaw, Rep NASA-TN-D-5777; L-6891, April 1970, 50 pages (Set Teth Aerospace Reps, 8 (12), 2157, N70-25256). 16 22. A study of adsorption and diffusion behaviour of hydrogen in palladium alloy systems. (USA) T h e absorption a n d diffusion behavaour of h y d r o g e n in various substitutional a n d interstitial alloys o f palladium was investigated by m e a n s o f electrochemical m e a s u r i n g techmques. It was f o u n d that the addition o f sdver, gold, or lead to the crystal lattice of palladium, alters the a b s o r p t i o n b e h a w o u r by e n h a n c i n g the initial h y d r o g e n solubility a n d by decreasing the solubility at high a m b i e n t hydrogen pressures K D Allard, Rep Vermont Untv, Microfilm No 69-20304, 244 pages (Sci Tech Aerospace Reps, 8 (12), 2158, N70-25291). 18. G A S E O U S E L E C T R O N I C S 18 23. Thermionic emission properties of transition metal monocarbides of IV or V group in the homogeneity region. ( G e r m a n y ) T h e dependence of work function on concentration is m e a s u r e d for titanium, zirconium, m o b m m a n d t a n t a l u m m o n o c a r b i d e s in a h o m o g e n e i t y range. Carbides are prepared by v a c u u m synthesis. T h e r m i o m c properties are Investigated In a n a p p a r a t u s with electron b e a m heating W o r k function is determined by the m e t h o d of saturation current in a t e m p e r a t u r e range o f 1500 to 2100°K. (USSR) V S F o m e a k o et al, Phys Status Sohdt (a), 2 (3), July 1970, K 1 8 1 - K I 8 4
(in German). 18 24. Emission cross sections of N2 in the vacuum ultraviolet by electron impact. T h e electron b e a m e x o t a t l o n s p e c t r u m o f N2 at low pressure (0.120.18 l0 m the wavelength range 1200-2000 ,~ was recorded for m o n o energetac electron impact energies f r o m l0 to 208 eV. T h e spectral features observed included Lyman-Bwge-Hopfield v t h r a h o n a l transih o n s and several atomic nitrogen multaplets produced by dassocaatwe excltataon o f N2. E m i s s i o n cross sectaons were m e a s u r e d a n d s u m m e d 62
to g~ve the cross section for the entire electronic transltaon. T h e a p p a r a t u s used included a n electron source, the electron beam excltataon c h a m b e r a n d a m o n o c h r o m a t o r with photomultapher detector. J M Ajella, J Chem Phys, 53 (3), 1 Aug 1970, 1156-1165 18 25. Investigation of plasma with hot electrons obtained at cyclotron resonance. ( U S S R ) At electron cyclotron resonance heating o f electrons w~th the m d of the wavegulde m e t h o d , h o t electrons wath a t e m p e r a t u r e of 80 keV a n d basic p l a s m a with a temperature o f 100 eV are obtained T h e dascharge is developed at neutral gas pressure of 2 IO ~ torr m the c h a m b e r , a n d for this reason a p l a s m a source ,s used m mare experiments. B I Patrushev et al, Zh tekh Fiz, 40 (7), July 1970, 1363-1370 (m
Ru~Man). 18 26. Measurement of electron energy distribution function in plasma at noise presence. (USSR) T h e electron energy d a s t n b u u o n function at fluctuations presence ,s m e a s u r e d with the and of a probe using a follower for space potential c o m p e n s a t i o n m a d,scharge in a maxture o f a r g o n at a pressure o f 0 6 torr, a n d m e r c u r y v a p o u r at a pressure of 2 5 ~ 10 -3 torr and a discharge current of 100 m A . Yu M K a g a n et al, Zh tekh Ftz, 40 (6), June 1970, 1319-1321 (m
Russian). 18 27. Some peealiarities of ultrahigh frequency oscillations in plasma of short arc discharge in caesium and mercury vapour. (USSR) T h e ultrahigh frequency oscdlatlons of a short caesium a n d m e r c u r y v a p o u r arc dascharge at a low pressure of 10 3 torr are investigated T h e dependence of o s c d l a h o n s on electron current distribution m p l a s m a is found. D Ya Dubko and S M Levitskiy, Zh tekh Ftz, 40 (6), June 1970, 1313
1317 (m Russian). 18 28. Space charge effects in high frequency gas discharge 11. (USSR) It is s h o w n that the course of radao frequency a n d pressure characterastics o f b r e a k d o w n in gases c a n be explained by space charge effects. T h e role of other processes in h,gh frequency discharge imitating m gases at m e d i u m pressure is discussed. G A Anashkin, Zh tekh Ftz, 40 (6), June 1970, 1262-1267 (in Ru.sstan). 18 29. Injection and maintenance of plasma in a closed quadrupole magnetic trap. (USSR) A n experimental apparatus, containing a stainless steel cylinder o f 1 m din. and 1 m length evacuated to pressure o f I 10 ~ torr, two coils for producing a q u a d r u p o l e magneUc field a n d a plasma source, is described. T h e posslbdaty of m a i n t a i n i n g h o t a n d dense plasma is investigated. V P Goneharenko et al, Zh tekh Fiz, 40 (6), June 1970, 1 2 0 6 1 2 1 6 (in
Russian). 18 30. Field emission from G a P . ( G e r m a n y ) Field emission f r o m G a P is investigated. T h e glass emission microscope wath stainless steel flanges for the d e m o u n t a b l e parts as used. T h e v a c u u m system cons,sts o f two m e r c u r y dlffUsaon p u m p s in ser,es with liquid m t r o g e n v a p o u r traps. T h e system pressure after t h o r o u g h b a k e o u t is higher t h a n 10 ~ torr. H y d r o g e n ion etching ~s a d o p t e d for cleaning the tap. T h e use o f l a n t h a n u m h e x a b o n d e coated filament iomzatlon gauge ~s essentml to prevent c o n t a m l n a t a o n o f the tip wath C O a n d HzO molecules which are released by heated tungsten filaments under the action of hydrogen T h e m e t h o d of preparation o f atomacally clean field emission tips on G a P single crystal is descrlbed. T h e G a P samples an the form o f wh,skers having a d m m e t e r of approxamately 50 /~m are m o u n t e d in the macroscope by c e m e n t i n g t h e m to a stainless steel bar. O n e a d v a n t a g e o f using samples m whisker form ts that the extremely high tensile strength of the materml results m very robust tips wh,ch withstand high d e s o r b m g fields without fracturing. T h e tip radii are of the order of 10 -2 cm. T h e currentvoltage plots obtained are f o u n d to be nonlinear, temperature dependent and photosensitive due to the high resistance of the materml. It is deduced that the emission arises from the valence b a n d of the semiconductor, the densaty o f surface states b e m g sufficient to prevent any field penetration. (USA) O H Hughes and P G Bristow, Phys Status Sohdt (a), 2 (3), July 1970, 503-509