Potential energy surface for the hydrogen–iodine reaction

Abstract

The potential energy surface for the Hz-I2 system was determined in analytic variational electronic structure calculations with single-and double-substitution configuration interactions for the 16 valence electrons and with effective potentials for the iodine core electrons. The favored pathway for the overall reaction H,+I,d HI + HI was found to pass through the region of the collinear configuration I-H-H-I. The pathway is accessible to bound and unbound iodine atom pairs and it allows the bimolecular and termolecular reactions, H,+ Iz-+ HI +HI and H,+I +I+HI +HI, both proposed by Bodenstein 100 years ago.

Mass Spectrometry of Free Radicals

“…The detection and characterization of free organic radicals has been one of the most important challenges for mass spectrometry during the past 60 years, and, for decades, free radicals have been fascinating species to chemists, mainly because of their elusive nature as intermediates in numerous chemical processes, such as atmospheric and interstellar chemistry, combustion, or chemical vapor deposition phenomena, which can make difficult the understanding of even the apparently most simple chemical processes. 1 If most of the information concerning the reactions of free radicals has come from kinetic studies in which the presence and behavior of radicals are mainly deduced from the nature of the reaction products and from the dependence of the observed reaction rates on various experimental parameters, mass spectrometry has early appeared as a direct method to study radical intermediates due to its immediate reponse in the analysis of representative samples of a reaction mixture. Another invaluable field where mass spectrometry of free radicals provided a wealth of information encompasses the field of bond energy determinations.…”

Mechanism of N2 Reduction to NH3 by Aqueous Solvated Electrons

“…Control experiments show no I − in the absence of H 2 . As such, while the exact mechanism is still debated, 76 it appears likely that H 2 product is being reoxidized under the current conditions. As a result, aqueous H + and I − are formed, consuming H 2 and I 2 , essentially serving to recombine the solvated electron with I atoms via a proton mediator.…”

Driving High Threshold Chemical Reactions by Cluster-Surface Collisions: Molecular Dynamics Simulations for CH3I Clusters

“…Concerted four-center collisions such as are nominally “forbidden” because of an unfavorable orbital correlation. , In a more refined view there is a curve crossing so that the reactants do correlate to the products but with a high barrier along the reaction coordinate. This high barrier has been discussed, e.g., for H 2 + H 2 3,4 and for HI + HI. − We − have suggested that such high barrier reactions could be thermally driven by cluster impact. In this approach, a cold, van der Waals bound cluster, in which the reactants are solvated, impacts a hard wall at a supersonic velocity. − Upon impact, a large fraction of the clusters have their (initially, directed) energy rapidly randomized, leading to ultrafast (tens of femtoseconds) heating.…”

“…This high barrier has been discussed, e.g., for H 2 + H 2 3,4 and for HI + HI. [5][6][7] We [8][9][10] have suggested that such high barrier reactions could be thermally driven by cluster impact. In this approach, a cold, van der Waals bound cluster, in which the reactants are solvated, impacts a hard wall at a supersonic velocity.…”