Topic
Valency
About: Valency is a research topic. Over the lifetime, 1632 publications have been published within this topic receiving 26141 citations.
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TL;DR: In this article, density functional theory methods are employed to take an in-depth look at hydrogenation reactions at transition metal surfaces, and a general correlation has also been found between the reaction barriers and the reaction potential energies.
Abstract: Hydrogenation reactions at transition metal surfaces comprise a key set of reactions in heterogeneous catalysis. In this paper, density functional theory methods are employed to take an in-depth look at this fundamental reaction type. The energetics of hydrogenation of atomic C, N, and O have been studied in some detail over low index Zr, Nb, Mo, Tc, Ru, Rh, and Pd surfaces. Detailed bonding analysis has also been employed to track carefully the chemical changes taking place during reaction. A number of interesting horizontal and vertical trends have been uncovered relating to reactant valency and metal d-band filling. A general correlation has also been found between the reaction barriers and the reaction potential energies. Moreover, when each reaction is considered independently, correlation has been found to improve with decreasing reactant valency. Bonding analysis has pointed to this being related to the relative position of the transition state along the reaction coordinate and has shown that as re...
14 citations
14 citations
TL;DR: In this article, the effect of H2 plasma exposure on CuInSe2 was studied by synchrotron radiation soft x-ray photoemission spectroscopy, and the results were correlated in order to relate changes in surface chemistry to the electronic structure.
Abstract: The effect of H2 plasma exposure on CuInSe2 was studied by synchrotron radiation soft‐x‐ray photoemission spectroscopy. The low‐power H2 plasma was generated with a commercial electron cyclotron resonance plasma source using pure H2 with the plasma exposure being performed at 200 °C. In situ photoemission measurements were acquired after each plasma exposure in order to observe changes in the valence‐band electronic structure as well as changes in the In 4d and Se 3d core lines. The results were correlated in order to relate changes in surface chemistry to the electronic structure. These measurements indicate that the H2 plasma exposure type converts the CuInSe2 surface to an n‐type surface as well as converting the In+3 valency state to an In+1 valency state.
13 citations
TL;DR: Proposals for building a new constructicon of English, based on the combination of the COBUILD Grammar Patterns and the semantic frames of FrameNet are described, finding that the automatic procedure must be complemented by a good deal of manual annotation.
Abstract: Recent research in construction grammar has been marked by increasing efforts to create constructicons: detailed inventories of form-meaning pairs to describe the grammar of a given language, following the principles of construction grammar. This paper describes proposals for building a new constructicon of English, based on the combination of the COBUILD Grammar Patterns and the semantic frames of FrameNet. In this case study, the valency information from FrameNet was automatically matched to the verb patterns of COBUILD, in order to identify the frames that each pattern is associated with. We find that the automatic procedure must be complemented by a good deal of manual annotation. We examine the “V that” pattern in particular, illustrating how the frame information can be used to describe this pattern in terms of constructions.
13 citations