scholarly journals The necessity of ultra-high vacuum for a reliable determination of hydrogen and carbon monoxide adsorption parameters.

Shinku ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 549-562 ◽  
Author(s):  
K. CHRISTMANN
Keyword(s):  
Carbon Monoxide ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Adsorption Parameters ◽  
Carbon Monoxide Adsorption ◽  
Reliable Determination

Comparative Studies of Pb/Cu(001) by TEM, AFM and STM

1998 ◽  
Vol 528 ◽  
Author(s):  
Franck Bocquet ◽  
Camille Cohen ◽  
Didier Schmaus ◽  
André Rocher ◽  
Jacques Crestou ◽  
...  
Keyword(s):  
Accurate Determination ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Specific Orientation

AbstractThe same specimen of Pb/Cu grown under Ultra High Vacuum (UHV) conditions has been investigated by Scanning Tunneling Microscopy (STM), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). We show that the information obtained by these techniques is consistent when comparable, and complementary. In particular, three different morphologies of Pb islands with specific orientation relationship are observed; AFM reveals the faceted shape of the islands; STM permits an accurate determination of the atomic structure of the facets; TEM moir6 patterns reveal that Pb islands are well relaxed.

Sticking probabilities, heats of adsorption and redistribution processes of nitrogen on tungsten films at 195 and 290 °K

1967 ◽  
Vol 297 (1450) ◽  
pp. 305-320 ◽  
Keyword(s):  
Accurate Determination ◽  
High Vacuum ◽  
Film Surface ◽  
Ultra High Vacuum ◽  
Weakly Bound ◽  
High Coverage ◽  
Heats Of Adsorption ◽  
Multiple Collisions ◽  
Accessible Surface

A kinetic investigation has been made of the interaction of nitrogen with evaporated films of tungsten prepared under ultra-high vacuum conditions. A technique is described for the accurate determination of the sticking probability of gases on metal films; the value for a clean film a t 290 °K (0·75) is higher than values reported for filaments or sheets, which have relatively smooth surfaces, and is attributed to multiple collisions at the film surface. At 195 and 290 °K, a redistribution process has been characterized, which, as in the hydrogen-molybdenum film system at 78 °K (Hayward, Taylor & Tompkins 1966), is due to the desorption of weakly held adsorbate from the outer, more accessible surface, and readsorption on to the inner porous structure of the film. Heats of adsorption for this weakly held state varied between 14 and 24 kcal/m ole. The redistribution process has been quantitatively treated utilizing an exponential variation of the activation energy for desorption with coverage. At high coverage an activated conversion of weakly bound to strongly bound adsorbate has been identified, this process being distinct from the redistribution between outer and inner surfaces of the film.

Determination of Surface Structure using Ultra‐High Vacuum Replication

1960 ◽  
Vol 31 (8) ◽  
pp. 1458-1462 ◽  
Author(s):  
L. Bachmann ◽  
W. H. Orr ◽  
T. N. Rhodin ◽  
B. M. Siegel
Keyword(s):  
Surface Structure ◽  
High Vacuum ◽  
Ultra High Vacuum

scholarly journals Carbon Monoxide Oxidation over Gold Nanoparticles Deposited onto Alumina Film Grown on Mo(110) Substrate: An Effect of Charge Tunneling through the Oxide Film

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 485
Author(s):  
Tamerlan Magkoev
Keyword(s):  
Carbon Monoxide ◽  
Oxide Film ◽  
Co Oxidation ◽  
Electron Tunneling ◽  
High Vacuum ◽  
Oxide System ◽  
Ultra High Vacuum ◽  
Excess Charge ◽  
Alumina Film ◽  
Oxidation Efficiency

Formation of gold nanosized particles supported by aluminum oxide film grown on Mo(110) substrate and oxidation of carbon monoxide molecules on their surface have been in-situ studied in ultra-high vacuum by means of Auger electron spectroscopy (AES), reflection-absorption infrared spectroscopy (RAIRS), low energy electron diffraction (LEED), atomic force microscopy (AFM), temperature-programmed desorption (TPD), and work function measurements. The main focus was to follow how the thickness of the alumina film influences the efficiency of CO oxidation in an attempt to find out evidence of the possible effect of electron tunneling between the metal substrate and the Au particle through the oxide interlayer. Providing the largest degree of surface identity of the studied metal/oxide system at different thicknesses of the alumina film (two, four, six, and eight monolayers), it was found that the CO oxidation efficiency, defined as CO2 to CO TPD peaks intensity ratio, exponentially decays with the oxide film thickness growth. Taking into account the known fact that the CO oxidation efficiency depends on the amount of excess charge acquired by Au particle, the latter suggests that electron tunneling adds efficiency to the oxidation process, although not significantly.

Thin Pyrolytic Graphite Films for Electron Microscope Substrates

1971 ◽  
Vol 29 ◽  
pp. 226-227 ◽  
Author(s):  
George H. N. Riddle ◽  
Benjamin M. Siegel
Keyword(s):  
Vacuum Chamber ◽  
Pyrolytic Graphite ◽  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Graphite Substrate ◽  
Nickel Substrate ◽  
Routine Procedure ◽  
Field Electron Microscopy ◽  
Dark Field Electron

A routine procedure for growing very thin graphite substrate films has been developed. The films are grown pyrolytically in an ultra-high vacuum chamber by exposing (111) epitaxial nickel films to carbon monoxide gas. The nickel serves as a catalyst for the disproportionation of CO through the reaction 2C0 → C + CO2. The nickel catalyst is prepared by evaporation onto artificial mica at 400°C and annealing for 1/2 hour at 600°C in vacuum. Exposure of the annealed nickel to 1 torr CO for 3 hours at 500°C results in the growth of very thin continuous graphite films. The graphite is stripped from its nickel substrate in acid and mounted on holey formvar support films for use as specimen substrates.The graphite films, self-supporting over formvar holes up to five microns in diameter, have been studied by bright and dark field electron microscopy, by electron diffraction, and have been shadowed to reveal their topography and thickness. The films consist of individual crystallites typically a micron across with their basal planes parallel to the surface but oriented in different, apparently random directions about the normal to the basal plane.

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