Search results for "dissociation"

Rate constants for ion-pair dissociation and association in the anionic two-state polymerization of styrene in THF

1965

An approach to polymer-supported triplet benzophenone photocatalysts. Application to sustainable photocatalysis of an α-diazocarbonyl compound

2013

Covalent immobilization of 4-hydroxybenzophenone on Merrifield resins affords new heterogeneous polymeric triplet photocatalysts. Their successful application in the intramolecular triplet-sensitized photolysis of a α-diazo β-keto ester has been achieved under sustainable criteria. Remarkably, the simple recovery and reuse for up to five sequential applications have been performed, although resulting in a slightly decreasing activity.

Photochemical Nitration by Tetranitromethane. Part XL. Regiochemistry of Trinitromethyl Attachment in the Photolysis of Benzofuran with Tetranitromet…

1997

Gold assisted oxygen dissociation on a molybdenum-doped CaO(001) surface

2016

Using density functional theory (DFT) calculations, we address the adsorption of O2 and the coadsorption of gold species and oxygen molecules on a Mo-doped CaO(001) surface with 1.25% impurity concentration. With the help of the Born–Haber thermodynamic cycle, the enhanced binding of an oxygen molecule on Ca(Mo)O is attributed to energy gain owing to simultaneous electron transfer from the dopant to the molecule and lattice relaxations. We consider three coadsorption structures for an Au atom and O2 molecule with different Au–O2 distances. The calculations demonstrate that the coadsorption structures take one electron from the dopant and the O–Au–O chain structure is thermodynamically more …

Photochemistry of the H2O/CO System Revisited : The HXeOH···CO Complex in a Xenon Matrix

2017

We report on the complex of a noble-gas hydride HXeOH with carbon monoxide. This species is prepared via the annealing-induced H + Xe + OH···CO reaction in a xenon matrix, the OH···CO complexes being produced by VUV photolysis of the H2O···CO complexes. The H–Xe stretching mode of the HXeOH···CO complex absorbs at 1590.3 cm–1 and it is blue-shifted by 12.7 cm–1 from the H–Xe stretching band of HXeOH monomer. The observed blue shift indicates the stabilization of the H–Xe bond upon complexation, which is characteristic of complexes of noble-gas hydrides. The HXeOH···CO species is the first complex of a noble-gas hydride with carbon monoxide and the second observed complex of HXeOH. On the ba…

PtTe2: Potential new material for the growth of defect-free TeO2 single crystals

2008

Abstract The dissociation of Te–O bonds is the main drawback, which hampers the yield of large-sized paratellurite single crystals of high optical quality when using platinum crucibles. In this work, it is assumed that a catalytic dissociation process involves the intermediate formation of platinum tellurides, these ones being then responsible for entrapment of gas bubbles and black precipitates when growth proceeds. To alleviate this difficulty, we suggest that platinum ditelluride could be a chemically more appropriate compound instead of pure platinum. First experiments on direct transformation of platinum sheets into PtTe 2 under tellurium gas atmosphere are described, as well as the pr…

Tailoring oxide properties: An impact on adsorption characteristics of molecules and metals

2014

Abstract Both density functional theory calculations and numerous experimental studies demonstrate a variety of unique features in metal supported oxide films and transition metal doped simple oxides, which are markedly different from their unmodified counterparts. This review highlights, from the computational perspective, recent literature on the properties of the above mentioned surfaces and how they adsorb and activate different species, support metal aggregates, and even catalyse reactions. The adsorption of Au atoms and clusters on metal-supported MgO films are reviewed together with the cluster׳s theoretically predicted ability to activate and dissociate O 2 at the Au–MgO(100)/Ag(100…

Toward the Understanding of the Photophysics and Photochemistry of 1-Nitronaphthalene under Solar Radiation: The First Theoretical Evidence of a Phot…

2015

1-Nitronaphthalene belongs to the class of nitrated polycyclic aromatic hydrocarbons, and constitutes an atmospheric pollutant commonly found in urban environments due to its production during incomplete combustions. On the basis of CASPT2//CASSCF quantum chemical calculations, the photophysics and photochemistry of the system under solar exposure have for the first time been studied. According to the characteristics of the incident radiation (either UVA or UVB, both present in the portion of the solar spectrum reaching the earth), a different excited state will be mainly populated. In both cases, the main decay path undertaken by the corresponding bright state leads to an efficient intersy…

Vibrational population of H 2 + after electroionization of thermal H2

1993

In an ion trap experiment we have determined the vibrational population of the lowest 9 vibrational levels of H2+. We used photodissociation of the trapped molecules by 248 nm light from an excimer laser and the dependence of the photodissociation cross section from the vibrational state. Our results are in good agreement to calculations, which are based on the Franck-Condon principle, but include a variation of the internuclear distance in the transition matrix element.

Water dissociation and water-gas shift energetics on MgO, MgO/Ag and Au/MgO/Ag surfaces

2011

Water dissociation and the energetics of the WGS reaction on a bulk MgO, an Ag supported MgO thin film and Au/MgO/Ag surfaces is studied based on the density functional theory. The literature results for water splitting on MgO and MgO/Ag surfaces with a step type defect are repeated and further analysis on the origin of the energetically favored dissociative water adsorption are made. The reactivity towards water dissociation on the stepped MgO and MgO/Ag surfaces is attributed to four contributing factors: 1. The change in the interlayer distance of the surface in dissociative adsorption is diminished on the stepped surfaces compared to the flat surfaces. On the flat surfaces the dissociat…