Theoretical calculation of the hydrogen negative ionization probability on the low work function surfaces

Chemical reactions at a surface will in most cases show a measurable influence on the work function of the clean surface. This change of the work function δφ can be used to image the local distributions of the investigated reaction,.if one of the reacting partners is adsorbed at the surface in form of islands of sufficient size (Δ>0.2μm). These can than be visualized via a photoemission electron microscope (PEEM). Changes of φ as low as 2 meV give already a change in the total intensity of a PEEM picture. To achieve reasonable contrast for an image several 10 meV of δφ are needed. Dynamic processes as surface diffusion of CO or O on single crystal surfaces as well as reaction / diffusion fronts have been observed in real time and space.

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Field-assisted ionization theory for microscopists

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100171833 ◽

1994 ◽

Vol 52 ◽

pp. 820-821

Author(s):

Patrick P. Camus

Keyword(s):

Electric Field ◽

Electron Tunneling ◽

Ionization Probability ◽

Critical Distance ◽

Tunneling Probability ◽

Field Ionization ◽

Radius Of Curvature ◽

Field Evaporation ◽

A Value ◽

Ion Emission

The theory of field ion emission is the study of electron tunneling probability enhanced by the application of a high electric field. At subnanometer distances and kilovolt potentials, the probability of tunneling of electrons increases markedly. Field ionization of gas atoms produce atomic resolution images of the surface of the specimen, while field evaporation of surface atoms sections the specimen. Details of emission theory may be found in monographs.Field ionization (FI) is the phenomena whereby an electric field assists in the ionization of gas atoms via tunneling. The tunneling probability is a maximum at a critical distance above the surface,xc, Fig. 1. Energy is required to ionize the gas atom at xc, I, but at a value reduced by the appliedelectric field, xcFe, while energy is recovered by placing the electron in the specimen, φ. The highest ionization probability occurs for those regions on the specimen that have the highest local electric field. Those atoms which protrude from the average surfacehave the smallest radius of curvature, the highest field and therefore produce the highest ionizationprobability and brightest spots on the imaging screen, Fig. 2. This technique is called field ion microscopy (FIM).

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Epitaxial ferroelectric thin films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100170591 ◽

1994 ◽

Vol 52 ◽

pp. 572-573

Author(s):

S. G. Ghonge ◽

E. Goo ◽

R. Ramesh ◽

R. Haakenaasen ◽

D. K. Fork

Keyword(s):

Single Crystal ◽

Work Function ◽

Nonvolatile Memory ◽

Ferroelectric Properties ◽

Electrical Contact ◽

Memory Devices ◽

Ferroelectric Films ◽

Si Substrates ◽

Electro Optic ◽

Wide Range

Microstructure of epitaxial ferroelectric/conductive oxide heterostructures on LaAIO3(LAO) and Si substrates have been studied by conventional and high resolution transmission electron microscopy. The epitaxial films have a wide range of potential applications in areas such as non-volatile memory devices, electro-optic devices and pyroelectric detectors. For applications such as electro-optic devices the films must be single crystal and for applications such as nonvolatile memory devices and pyroelectric devices single crystal films will enhance the performance of the devices. The ferroelectric films studied are Pb(Zr0.2Ti0.8)O3(PLZT), PbTiO3(PT), BiTiO3(BT) and Pb0.9La0.1(Zr0.2Ti0.8)0.975O3(PLZT).Electrical contact to ferroelectric films is commonly made with metals such as Pt. Metals generally have a large difference in work function compared to the work function of the ferroelectric oxides. This results in a Schottky barrier at the interface and the interfacial space charge is believed to responsible for domain pinning and degradation in the ferroelectric properties resulting in phenomenon such as fatigue.

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Work function in studying mechanism and kinetics of heterogeneous reactions in the system : oxygen-nonstoichiometric oxides

Journal de Chimie Physique ◽

10.1051/jcp/1978750689 ◽

1978 ◽

Vol 75 ◽

pp. 689-702 ◽

Cited By ~ 10

Author(s):

Janusz Nowotny

Keyword(s):

Work Function ◽

Heterogeneous Reactions ◽

Nonstoichiometric Oxides ◽

Mechanism And Kinetics ◽

Kinetics Of

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Theoretical calculation of localized heating caused by interaction of ultrasound and microcrack

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:2005125125 ◽

2005 ◽

Vol 125 ◽

pp. 539-541 ◽

Cited By ~ 1

Author(s):

X. B. Mi ◽

S. Y. Zhang ◽

X. Y. Han

Keyword(s):

Theoretical Calculation ◽

Localized Heating

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Analysis of electro- and thermophysical processes occurring during electrocontact baking of flour products.

Khleboproducty ◽

10.32462/0235-2508-2020-29-11-50-55 ◽

2020 ◽

Vol 29 (11) ◽

pp. 50-55

Author(s):

V.I. Maklyukov ◽

◽

E.O. Gerasimova ◽

N. V. Labutina ◽

E.N. Rogozkin ◽

...

Keyword(s):

Electrical Conductivity ◽

Theoretical Calculation ◽

Heat Balance ◽

Electric Contact ◽

Wheat Dough ◽

Baking Process ◽

Free Moisture ◽

Contact Heating ◽

The Heat Balance

The article considers the results of research conducted during electric contact heating of rye-wheat dough pieces. It is established that the electrical conductivity of the crumb dough does not depend on the total humidity of the material, but mainly on the amount of free moisture. Using the current and temperature graphs, you can imagine how free moisture changes during the baking process and the influence of the thermophysical and colloidal process on the change in the value of free moisture. Experimentally determined the amount of heat that is spent on baking 1 kg of bread. The accuracy of the theoretical calculation of this parameter in the heat balance of the baking chamber is confirmed.

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