The anomalous high reactivity of Ca+ with S8 in the gas phase: [CaS3]+ and [CaS11]+

1995 ◽  
pp. 975 ◽  
Author(s):  
Ian G. Dance ◽  
Keith J. Fisher ◽  
Gary D. Willett
Keyword(s):  
Gas Phase ◽  
High Reactivity

scholarly journals Variable lifetimes and loss mechanisms for NO<sub>3</sub> and N<sub>2</sub>O<sub>5</sub> during the DOMINO campaign: contrasts between marine, urban and continental air

2011 ◽  
Vol 11 (6) ◽  
pp. 17825-17877
Author(s):  
J. N. Crowley ◽  
J. Thieser ◽  
M. Tang ◽  
G. Schuster ◽  
H. Bozem ◽  
...  
Keyword(s):  
Gas Phase ◽  
High Reactivity ◽  
Heterogeneous Reactions ◽  
Urban Air ◽  
Industrial Complex ◽  
Atlantic Sector ◽  
Air Masses ◽  
Mixing Ratios ◽  
Nighttime Chemistry ◽  
Heterogeneous Processes

Abstract. Nighttime mixing ratios of boundary layer N2O5 were determined using cavity-ring-down spectroscopy during the DOMINO campaign. Observation of N2O5 was intermittent, with mixing ratios ranging from below the detection limit (~5 ppt) to ~500 ppt. A steady-state analysis constrained by measured mixing ratios of NO2 and O3 was used to derive NO3 lifetimes and compare them to calculated rates of loss via gas-phase and heterogeneous reactions of both NO3 and N2O5. Three distinct types of air masses were encountered, which were largely marine (Atlantic), continental or urban-industrial in origin. NO3 lifetimes were longest in the Atlantic sector (up to ~30 min) but were very short (a few seconds) in polluted, air masses from the local city and petroleum-related industrial complex of Huelva. Air from the continental sector was an intermediate case. The high reactivity to NO3 of the urban air mass was not accounted for by gas-phase and heterogeneous reactions, rates of which were constrained by measurements of NO, volatile organic species and aerosol surface area. In general, high NO2 mixing ratios resulted in low NO3 lifetimes, though heterogeneous processes (e.g. reaction of N2O5 on aerosol) were generally less important than direct gas-phase losses of NO3. The presence of SO2 at levels above ~2 ppb in the urban air sector was always associated with very low N2O5 mixing ratios indicating either very short NO3 lifetimes in the presence of combustion-related emissions or an important role for reduced sulphur species in urban, nighttime chemistry. High production rates coupled with low lifetimes of NO3 imply an important contribution of nighttime chemistry to removal of both NOx and VOC.

scholarly journals Water Radical Cations in the Gas Phase: Methods and Mechanisms of Formation, Structure and Chemical Properties

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3490
Author(s):  
Dongbo Mi ◽  
Konstantin Chingin
Keyword(s):  
Gas Phase ◽  
Water Clusters ◽  
Current Knowledge ◽  
Chemical Properties ◽  
Radical Cations ◽  
High Reactivity ◽  
Natural Processes ◽  
Mechanisms Of Formation ◽  
Primary Ions ◽  
And Chemical Properties

Water radical cations, (H2O)n+•, are of great research interest in both fundamental and applied sciences. Fundamental studies of water radical reactions are important to better understand the mechanisms of natural processes, such as proton transfer in aqueous solutions, the formation of hydrogen bonds and DNA damage, as well as for the discovery of new gas-phase reactions and products. In applied science, the interest in water radicals is prompted by their potential in radiobiology and as a source of primary ions for selective and sensitive chemical ionization. However, in contrast to protonated water clusters, (H2O)nH+, which are relatively easy to generate and isolate in experiments, the generation and isolation of radical water clusters, (H2O)n+•, is tremendously difficult due to their ultra-high reactivity. This review focuses on the current knowledge and unknowns regarding (H2O)n+• species, including the methods and mechanisms of their formation, structure and chemical properties.

Gas-phase heteroaromatic substitution. 10. Reaction of free phenylium ion with simple five-membered heteroarenes in the gaseous and liquid phase

1991 ◽  
Vol 69 (4) ◽  
pp. 732-739 ◽  
Author(s):  
Antonello Filippi ◽  
Giorgio Occhiucci ◽  
Maurizio Speranza
Keyword(s):  
Electron Transfer ◽  
Gas Phase ◽  
High Reactivity ◽  
Ion Chemistry ◽  
Β Decay ◽  
Reactivity Pattern ◽  
Gas Phase Ion Chemistry ◽  
Liquid Phases ◽  
Ionic Intermediates ◽  
Gas Phase Ion

Phenylium ion, obtained from the spontaneous β decay of 1,4-ditritiobenzene, has been allowed to react with pyrrole, N-methylpyrrole, furan, and thiophene, in both the gaseous and liquid phases. The differences between the reactivity pattern of phenylium ion in the two environments can be essentially reduced to significant ion-neutral electrostatic interaction in the gas phase and to the much greater efficiency of collisional stabilization in the condensed phase, allowing a larger fraction of the excited ionic intermediates, from the highly exothermic attack of phenylium ion on the aromatic substrate, to survive dissociation and isomerization. The mechanism of the phenylation process and of the subsequent isomerization of the relevant ionic intermediates is discussed and the intrinsic substrate and positional selectivity of the phenylium ion evaluated. While the limited substrate discrimination of phenylium ion fully agrees with its well-known exceedingly high reactivity, its pronounced affinity toward the α carbons of the selected heteroarenes does not conform with the relatively "hard" character of the reactant, expected on the grounds of its STO-3G calculated LUMO energy. The conceivable occurrence of an intimate entropy-favored two-step addition mechanism, involving a preliminary single-electron transfer (SET) from the heteroaromatic substrate to the ionic electrophile, which is thermochemically allowed only for phenylium and methyl cations and prevented for other alkylating electrophiles, is discussed. Key words: gas-phase ion chemistry, electrophilic heteroaromatic substitution, nuclear decay chemistry, phenylium ion, electron transfer.

scholarly journals Variable lifetimes and loss mechanisms for NO<sub>3</sub> and N<sub>2</sub>O<sub>5</sub> during the DOMINO campaign: contrasts between marine, urban and continental air

2011 ◽  
Vol 11 (21) ◽  
pp. 10853-10870 ◽  
Author(s):  
J. N. Crowley ◽  
J. Thieser ◽  
M. J. Tang ◽  
G. Schuster ◽  
H. Bozem ◽  
...  
Keyword(s):  
Gas Phase ◽  
High Reactivity ◽  
Heterogeneous Reactions ◽  
Urban Air ◽  
Industrial Complex ◽  
Atlantic Sector ◽  
Air Masses ◽  
Mixing Ratios ◽  
Nighttime Chemistry ◽  
Heterogeneous Processes

Abstract. Nighttime mixing ratios of boundary layer N2O5 were determined using cavity-ring-down spectroscopy during the DOMINO campaign in Southern Spain (Diel Oxidant Mechanisms In relation to Nitrogen Oxides, 21 November 2008–8 December 2008). N2O5 mixing ratios ranged from below the detection limit (~5 ppt) to ~500 ppt. A steady-state analysis constrained by measured mixing ratios of N2O5, NO2 and O3 was used to derive NO3 lifetimes and compare them to calculated rates of loss via gas-phase and heterogeneous reactions of both NO3 and N2O5. Three distinct types of air masses were encountered, which were largely marine (Atlantic), continental or urban-industrial in origin. NO3 lifetimes were longest in the Atlantic sector (up to ~30 min) but were very short (a few seconds) in polluted, air masses from the local city and petroleum-related industrial complex of Huelva. Air from the continental sector was an intermediate case. The high reactivity to NO3 of the urban air mass was not accounted for by gas-phase and heterogeneous reactions, rates of which were constrained by measurements of NO, volatile organic species and aerosol surface area. In general, high NO2 mixing ratios were associated with low NO3 lifetimes, though heterogeneous processes (e.g. reaction of N2O5 on aerosol) were generally less important than direct gas-phase losses of NO3. The presence of SO2 at levels above ~2 ppb in the urban air sector was always associated with very low N2O5 mixing ratios indicating either very short NO3 lifetimes in the presence of combustion-related emissions or an important role for reduced sulphur species in urban, nighttime chemistry. High production rates coupled with low lifetimes of NO3 imply an important contribution of nighttime chemistry to removal of both NOx and VOC.

scholarly journals FLUORESCENCE HISTOCHEMISTRY OF BIOGENIC MONOAMINES A STUDY OF THE CAPACITY OF VARIOUS CARBONYL COMPOUNDS TO FORM FLUOROPHORES WITH BIOGENIC MONOAMINES IN GAS PHASE REACTIONS

1972 ◽  
Vol 20 (6) ◽  
pp. 435-444 ◽  
Author(s):  
STURE AXELSSON ◽  
ANDERS BJÖRKLUND ◽  
OLLE LINDVALL
Keyword(s):  
Acetic Acid ◽  
Gas Phase ◽  
Carbonyl Compounds ◽  
Glyoxylic Acid ◽  
Histochemical Demonstration ◽  
High Reactivity ◽  
Gas Phase Reactions ◽  
Cyclization Reactions ◽  
Biogenic Monoamines ◽  
Keto Acids

The capacity of biogenic amines to form fluorophores in histochemical gas phase reactions has been tested with 20 compounds having a carbonyl group (> C = O) as a common characteristic. Significant visible fluorescence was induced from catecholamines and indolamines with aldehydes, ketones, α-keto acids and carboxylic acids, suggesting that all of these compounds can enter fluorophore-forming cyclization reactions under the histochemical gas phase conditions. The most "reactive" reagents are found among the low molecular aldehydes, and formaldehyde and glyoxylic acid seem to be the most suitable reagents, combining high reactivity with good selectivity. Fluorescence, interesting for the histochemical demonstration of N-acetylated indolamines, was obtained from melatonin and N-acetyl-5-hydroxytryptamine with some acid reagents (glyoxylic acid, formic acid, acetic acid and pyruvic acid). A direct cyclodehydration according to the classical Bischler-Napieralski reaction is the most likely mechanism underlying this fluorophore formation. The usefulness of the various carbonyl reagents for the fluorescence histochemical demonstration of other biologically interesting amines, such as histamine, p-tyramine and octopamine, has been specially investigated.

scholarly journals Observation of the simplest Criegee intermediate CH2OO in the gas-phase ozonolysis of ethylene

2015 ◽  
Vol 1 (2) ◽  
pp. e1400105 ◽  
Author(s):  
Caroline C. Womack ◽  
Marie-Aline Martin-Drumel ◽  
Gordon G. Brown ◽  
Robert W. Field ◽  
Michael C. McCarthy
Keyword(s):  
Fourier Transform ◽  
Gas Phase ◽  
Rate Constants ◽  
Qualitative Agreement ◽  
High Reactivity ◽  
Microwave Spectroscopy ◽  
Bimolecular Reactions ◽  
Rapid Sampling ◽  
Product Species ◽  
Pulsed Nozzle

Ozonolysis is one of the dominant oxidation pathways for tropospheric alkenes. Although numerous studies have confirmed a 1,3-cycloaddition mechanism that generates a Criegee intermediate (CI) with form R1R2COO, no small CIs have ever been directly observed in the ozonolysis of alkenes because of their high reactivity. We present the first experimental detection of CH2OO in the gas-phase ozonolysis of ethylene, using Fourier transform microwave spectroscopy and a modified pulsed nozzle, which combines high reactant concentrations with rapid sampling and sensitive detection. Nine other product species of the O3+ C2H4reaction were also detected, including formaldehyde, formic acid, dioxirane, and ethylene ozonide. The presence of all these species can be attributed to the unimolecular and bimolecular reactions of CH2OO, and their abundances are in qualitative agreement with published mechanisms and rate constants.

scholarly journals Effect of nano metal oxides on heme molecule: molecular and biomolecular approaches

2019 ◽  
Vol 10 (1) ◽  
pp. 4837-4845
Keyword(s):  
Gas Phase ◽  
Complex Structure ◽  
Geometry Optimization ◽  
Complex Form ◽  
High Reactivity ◽  
Quantum Mechanical ◽  
Interacting Species ◽  
Heme Structure ◽  
Main Component ◽  
Heme Molecule

Interaction of components of living cells with various nanomaterials in the gas phase has been one of extensive concern since they become intensively utilized in various life aspects. This work is carried out to investigate the interaction between heme molecule, as the main component of hemoglobin, with several familiar and non-familiar divalent structures such as O2, CO2, CO, MgO, CoO, NiO, CuO and ZnO. Geometry optimization processes as well as QSAR descriptors are conducted using semiemprical quantum mechanical calculations at PM6 level. Results illustrate that adsorbing O2 and CO on heme lowers their TDM helping heme in performing its transportation function and not interacting with other species. On the other hand, when CoO and ZnO interacting with heme the TDM of the resultant structures increase greatly reflecting high reactivity which may interact with other species more than performing its function. Therefore, interacting species other than O2 may disturb the transportation function of heme structure. QSAR data of IP regarding interaction of O2 with heme ensure the TDM result that reflects lowering its activity. IP of H-CO adsorbed is the lowest indicating high reactivity while those of H-O2, H-CO2, H-MgO and H-NiO in the complex form are the highest values indicating that it is difficult to form a complex structure with them. Therefore, heme interactions with structures rather than O2 and CO2 affects negatively its function as gas transporter.

Residual Gas Reactions in the Electron Microscope: I. Qualitative Observations on the Water Gas Reaction

1968 ◽  
Vol 26 ◽  
pp. 292-293
Author(s):  
Richard E. Hartman ◽  
Roberta S. Hartman ◽  
Peter L. Ramos
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Gas Phase ◽  
Absolute Temperature ◽  
Residual Gas ◽  
Gas Reactions ◽  
Image Position ◽  
The Right ◽  
Water Gas ◽  
Thinning Rate

The action of water and the electron beam on organic specimens in the electron microscope results in the removal of oxidizable material (primarily hydrogen and carbon) by reactions similar to the water gas reaction .which has the form:The energy required to force the reaction to the right is supplied by the interaction of the electron beam with the specimen.The mass of water striking the specimen is given by:where u = gH2O/cm2 sec, PH2O = partial pressure of water in Torr, & T = absolute temperature of the gas phase. If it is assumed that mass is removed from the specimen by a reaction approximated by (1) and that the specimen is uniformly thinned by the reaction, then the thinning rate in A/ min iswhere x = thickness of the specimen in A, t = time in minutes, & E = efficiency (the fraction of the water striking the specimen which reacts with it).

Integration of Core-Edge Spectroscopy Methods for the Study of Polymers

1996 ◽  
Vol 54 ◽  
pp. 154-155
Author(s):  
E. G. Rightor
Keyword(s):  
Excited State ◽  
Polymer Blends ◽  
Gas Phase ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Electronic States ◽  
Core Electron ◽  
Bulk Solids ◽  
Development Application

Core edge spectroscopy methods are versatile tools for investigating a wide variety of materials. They can be used to probe the electronic states of materials in bulk solids, on surfaces, or in the gas phase. This family of methods involves promoting an inner shell (core) electron to an excited state and recording either the primary excitation or secondary decay of the excited state. The techniques are complimentary and have different strengths and limitations for studying challenging aspects of materials. The need to identify components in polymers or polymer blends at high spatial resolution has driven development, application, and integration of results from several of these methods.

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