When does electronic delocalization become a driving force of chemical bonding?

1988 ◽  
Vol 92 (18) ◽  
pp. 5086-5094 ◽  
Author(s):  
Sason S. Shaik ◽  
Philippe C. Hiberty ◽  
Gilles Ohanessian ◽  
Jean Michel Lefour
Keyword(s):  
Chemical Bonding ◽  
Driving Force ◽  
Electronic Delocalization

Embrittlement of Cracks at Interfaces

1995 ◽  
Vol 408 ◽  
Author(s):  
Robb Thomson ◽  
Emeritus ◽  
A. E. Carlsson
Keyword(s):  
Chemical Bonding ◽  
Driving Force ◽  
Driving Forces ◽  
Interface Analysis ◽  
Analytic Approximations ◽  
The Matrix ◽  
Block Construction ◽  
Lattice Resistance

AbstractThis paper presents a synopsis of already published work for cracks on interfaces and new results on the effect of changing the chemistry of the atoms at the interface. Once the appropriate cut-off for the oscillatory singularity in the interface analysis is determined, the physics of the crack is determined in terms of an appropriate driving force for a particular event of interest, and a lattice resistance to the event. Analytic approximations are available for the driving forces, and the lattice resistance is determined on the basis of a block construction for the lattice. We show that for the case where the chemical bonding at the interface is different from that in the matrix, the same ideas are applicable, provided the different chemistry is incorporated correctly in the lattice resistance construction.

Embrittlement of Cracks at Interfaces.

1995 ◽  
Vol 409 ◽  
Author(s):  
Robb Thomson Emeritus ◽  
A. E. Carlsson
Keyword(s):  
Chemical Bonding ◽  
Driving Force ◽  
Driving Forces ◽  
Interface Analysis ◽  
Analytic Approximations ◽  
The Matrix ◽  
Block Construction ◽  
Lattice Resistance

AbstractThis paper presents a synopsis of already published work for cracks on interfaces and new results on the effect of changing the chemistry of the atoms at the interface. Once the appropriate cut-off for the oscillatory singularity in the interface analysis is determined, the physics of the crack is determined in terms of an appropriate driving force for a particular event of interest, and a lattice resistance to the event. Analytic approximations are available for the driving forces, and the lattice resistance is determined on the basis of a block construction for the lattice. We show that for the case where the chemical bonding at the interface is different from that in the matrix, the same ideas are applicable, provided the different chemistry is incorporated correctly in the lattice resistance construction.

Crystal growth: an anisotropic mass transfer process at the interface

2017 ◽  
Vol 19 (19) ◽  
pp. 12407-12413 ◽  
Author(s):  
Congting Sun ◽  
Dongfeng Xue
Keyword(s):  
Mass Transfer ◽  
Crystal Growth ◽  
Transfer Process ◽  
Chemical Bonding ◽  
Driving Force ◽  
Mass Transfer Process

Mass transfer of growth units towards the interface promotes crystal growth, and the driving force essentially depends on anisotropic chemical bonding architectures.

scholarly journals Expanding the usage of the Source Function to experimental electron densities

2016 ◽  
Vol 72 (2) ◽  
pp. 169-170
Author(s):  
Jacob Overgaard
Keyword(s):  
Solid State ◽  
Chemical Bonding ◽  
Source Function ◽  
Electron Densities ◽  
X Ray ◽  
Unique Information ◽  
Electronic Delocalization ◽  
Aromatic Systems

The Source Function provides unique information about chemical bonding in the solid state, from theory as well as from experiment. It is now established that the concept of electronic delocalization in aromatic systems can be accurately studied using X-ray derived electron densities, and even more importantly the contributions are transferable between similar systems.

When does electronic delocalization become a driving force of molecular shape and stability? 1. The aromatic sextet

1985 ◽  
Vol 107 (11) ◽  
pp. 3089-3095 ◽  
Author(s):  
Sason S. Shaik ◽  
Philippe C. Hiberty
Keyword(s):  
Driving Force ◽  
Molecular Shape ◽  
Electronic Delocalization

Radiation-induced surface decomposition

1983 ◽  
Vol 41 ◽  
pp. 368-369
Author(s):  
M. L. Knotek
Keyword(s):  
Ionizing Radiation ◽  
Atomic Structure ◽  
Chemical Bonding ◽  
Neutral Species ◽  
Radiation Induced ◽  
Physical And Chemical ◽  
Surface Decomposition ◽  
The Relationship ◽  
Electron And Photon ◽  
Surface Bond

Modern surface analysis is based largely upon the use of ionizing radiation to probe the electronic and atomic structure of the surfaces physical and chemical makeup. In many of these studies the ionizing radiation used as the primary probe is found to induce changes in the structure and makeup of the surface, especially when electrons are employed. A number of techniques employ the phenomenon of radiation induced desorption as a means of probing the nature of the surface bond. These include Electron- and Photon-Stimulated Desorption (ESD and PSD) which measure desorbed ionic and neutral species as they leave the surface after the surface has been excited by some incident ionizing particle. There has recently been a great deal of activity in determining the relationship between the nature of chemical bonding and its susceptibility to radiation damage.

In situ TEM Studies of agglomeration of sub-nanometer Ru layers in Ru/C multilayers

1992 ◽  
Vol 50 (1) ◽  
pp. 256-257
Author(s):  
Tai D. Nguyen ◽  
Ronald Gronsky ◽  
Jeffrey B. Kortright
Keyword(s):  
Layered Structure ◽  
Driving Force ◽  
High Energy ◽  
Superior Performance ◽  
In Situ Tem ◽  
Rayleigh Instability ◽  
Practical Applications ◽  
Transmission Electron ◽  
Diffraction Patterns

Nanometer period Ru/C multilayers are one of the prime candidates for normal incident reflecting mirrors at wavelengths < 10 nm. Superior performance, which requires uniform layers and smooth interfaces, and high stability of the layered structure under thermal loadings are some of the demands in practical applications. Previous studies however show that the Ru layers in the 2 nm period Ru/C multilayer agglomerate upon moderate annealing, and the layered structure is no longer retained. This agglomeration and crystallization of the Ru layers upon annealing to form almost spherical crystallites is a result of the reduction of surface or interfacial energy from die amorphous high energy non-equilibrium state of the as-prepared sample dirough diffusive arrangements of the atoms. Proposed models for mechanism of thin film agglomeration include one analogous to Rayleigh instability, and grain boundary grooving in polycrystalline films. These models however are not necessarily appropriate to explain for the agglomeration in the sub-nanometer amorphous Ru layers in Ru/C multilayers. The Ru-C phase diagram shows a wide miscible gap, which indicates the preference of phase separation between these two materials and provides an additional driving force for agglomeration. In this paper, we study the evolution of the microstructures and layered structure via in-situ Transmission Electron Microscopy (TEM), and attempt to determine the order of occurence of agglomeration and crystallization in the Ru layers by observing the diffraction patterns.

The nucleation of cavities at grain boundaries

1987 ◽  
Vol 45 ◽  
pp. 288-291
Author(s):  
P. J. Goodhew
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Grain Boundaries ◽  
Radiation Damage ◽  
Impurity Concentration ◽  
Driving Force ◽  
Nucleation And Growth ◽  
Phase Boundaries ◽  
Cavity Nucleation ◽  
Spherical Bubble

Cavity nucleation and growth at grain and phase boundaries is of concern because it can lead to failure during creep and can lead to embrittlement as a result of radiation damage. Two major types of cavity are usually distinguished: The term bubble is applied to a cavity which contains gas at a pressure which is at least sufficient to support the surface tension (2g/r for a spherical bubble of radius r and surface energy g). The term void is generally applied to any cavity which contains less gas than this, but is not necessarily empty of gas. A void would therefore tend to shrink in the absence of any imposed driving force for growth, whereas a bubble would be stable or would tend to grow. It is widely considered that cavity nucleation always requires the presence of one or more gas atoms. However since it is extremely difficult to prepare experimental materials with a gas impurity concentration lower than their eventual cavity concentration there is little to be gained by debating this point.

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