Elementary reaction

About: Elementary reaction is a research topic. Over the lifetime, 2972 publications have been published within this topic receiving 76110 citations.

Reaction Rates and Affinities

Abstract: A new definition of elementary reactions is being based upon the Marcelin‐De Donder formulation of reaction rates. Complex reactions resulting from sequences of elementary reactions are examined, under steady‐state conditions, both close to, and far from equilibrium. In the former case the over‐all rate is proportional to the over‐all affinity, while in the latter case, when all steps are far from their equilibria, the over‐all rate varies exponentially with the over‐all forward affinity. The problem of the identification of rate‐determining steps is discussed on the basis of the adopted definition of elementary reactions. Application of the treatment to the two‐step sequence A + B⇌C, C→D+E leads to a close connection with the absolute rate theory.

Density functional theory‐based electrochemical models for the oxygen reduction reaction: Comparison of modeling approaches for electric field and solvent effects

Abstract: A series of density functional theory (DFT) based electrochemical models are applied to systematically examine the effect of solvent, local electric field, and electrode potential on oxygen reduction reaction (ORR) kinetics. Specifically, the key elementary reaction steps of molecular oxygen dissociation, molecular oxygen protonation, and reduction of a hydroxyl adsorbate to water over the Pt(111) surface were considered. The local electric field has slight influence on reaction energetics at the vacuum interface. Solvent molecules stabilize surface adsorbates, assisting oxygen reduction. A collective solvation-potential coupled effect is identified by including long range solvent-solvent interactions in the DFT model. The dominant path of the ORR reaction varies with electrode potential and among the modeling approaches considered. The potential dependent reaction path determined from the solvated model qualitatively agrees with experiment ORR kinetics. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011

Elementary reactions of NH(a1Δ) and NH(X3Σ) with N, O and NO

Abstract: The elementary reactions of NH(a1Δ) with N, O, and NO and the reactions of NH(X3Σ−) with N, O and NO were studied in a quasi static laser flash photolysis cell at room temperature (T=298T) and low pressures (15≤p/mbar≤20). NH(a) was produced by HN3 laser photolysis at λ = 248 nm. NH(X) was obtained from the fast quenching of NH(a) with Xe. The O atom source was the NO + N reaction ([N]0>>[NO]0), with N atoms formed in a microwave discharge of N2/He. NH(a), NO(X) and the primary products NH(X), OH(X) and NO (X) were detected by pulsed laser induced fluorescence (LIF). The absolute N atom concentrations were determined via the reaction of N with NO. Time resolution was achieved by time delay between photolysis and probe laser pulses. For overall depletion: the following rate constants were obtained: k1, = (6.0±1.5)·1011 cm3/(mol·s); k2 = (5.6±2)·1012cm3/(mol·s); and k3 = (1.8±0.2)·1013 cm3(mol·s). By fitting the NH(X) concentration profiles, determined experimentally, with computer simulations, the following rate constants for quenching channels were obtained: k1q = (6.0±1.2)·1011 cm3/(mol·s) and k2q = (1.2±0.3)·1012cm3/(mol·s). For the reaction pathways of reaction (2):

Product State Resolved Dynamics of Elementary Reactions

Abstract: We describe how the photon-initiated reaction technique has been used to provide dynamical information about elementary gas-phase bimolecular reactions at the product quantum state-resolved level. ...