Reactions of alcohols adsorbed on MgO. Part I. Heterogeneous reactions with hydrogen atoms and trapped electrons at room temperature: a new technique in surface chemistry

1969 ◽  
Vol 47 (8) ◽  
pp. 1381-1389 ◽  
Author(s):  
D. R. Smith ◽  
A. J. Tench
Keyword(s):  
Allyl Alcohol ◽  
Room Temperature ◽  
Heterogeneous Reactions ◽  
Hydrogen Atoms ◽  
Hydrogen Elimination ◽  
Oxygen Ion ◽  
Spin Resonance ◽  
A New Technique ◽  
Mgo Surface ◽  
Alcohol Radical

A series of alcohols, adsorbed on MgO powder, have been bombarded by a stream of hydrogen atoms at room temperature and the radicals thus formed are detected by electron spin resonance. Methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and allyl alcohol have been studied. The radical species produced have been identified and radical lifetimes varying from minutes to hours at 300 °K have been observed. For methanol, the first monolayer appears to be chemisorbed as methoxy groups whereas the ethanol data indicate that some of the molecules in the first monolayer are physically adsorbed. The higher alcohols form secondary radicals via hydrogen elimination from the primary radical; the isopropyl alcohol radical appears to isomerize before losing hydrogen. Allyl alcohol undergoes hydrogen atom abstraction in preference to addition to the double bond and yields the α-hydroxy-allyl radical. Methanol and ethanol have also been reacted with electrons trapped on a MgO surface to form stable alkoxide ion radicals trapped at oxygen ion vacancies on the surface of the lattice.

The measurement of the rate of recombination of hydrogen atoms at room temperature by means of e. s. r. spectroscopy

1968 ◽  
Vol 305 (1483) ◽  
pp. 553-574 ◽  
Keyword(s):  
Gas Flow ◽  
Room Temperature ◽  
Statistical Treatment ◽  
Resonance Spectroscopy ◽  
Small Contribution ◽  
Hydrogen Atoms ◽  
Third Order ◽  
Spin Resonance ◽  
Viscous Pressure ◽  
Kinetics Of

Electron spin resonance spectroscopy has been used to determine the absolute concentrations of hydrogen atoms in a gas-flow system at room temperature and at total pressures between 1 and 10 Torr. The kinetics of the decay of hydrogen atoms in the presence of undissociated molecular hydrogen have been extensively analysed on the basis of a statistical treatment of errors for a model which includes first- and second-order decay processes and axial diffusion of the atoms. Care has been taken to consider the effects of high (up to about 20%) dissociation of hydrogen, of viscous pressure drop along the reaction tube, and of other possible decay processes. The predominant rate of removal of hydrogen atoms was by the reaction K 2 H+H+H 2 →H 2 +H 2 , and the value of k 2 was 2·7±0·4x10 15 cm 6 mole -2 s -1 . A small contribution from a first-order reaction K 1 H→ 1 / 2 H 2 (presumably a wall reaction) was also found. The rate constant, k 1, was 0·21±0·15s -1 , which corresponds, in the case of a wall process, to a wall efficiency of 6·5±4·6x10 -7 . No evidence could be found for the presence of the third-order process K 2 H+H+H→H 2 +H, and an upper limit for k 3 could therefore be set at 5·0x1015 cm 6 mole -2 s -1

ESR of Paramagnetic Species Produced by Gamma Irradiation in Cadmium Oxalate Three Hydrate Single Crystal

1976 ◽  
Vol 31 (1) ◽  
pp. 80-83 ◽  
Author(s):  
F. Köksal ◽  
H. Yiiksel
Keyword(s):  
Gamma Irradiation ◽  
Single Crystal ◽  
Unpaired Electron ◽  
Room Temperature ◽  
Paramagnetic Species ◽  
Temperature Analysis ◽  
Hydrogen Atoms ◽  
Radical Species ◽  
Average Value ◽  
Spin Resonance

Paramagnetic species produced in a single crystal of cadmium oxalate three hydrate (CdC2O4 · 3H2O) by gamma irradiation have been investigated with the method of electron spin resonance. Only one radical species was observed at room temperature. Analysis of the experimental results leads to the conclusion that the species has the form RCHOH in which the unpaired electron is concentrated at the carbon atom and interacts with the two hydrogen atoms. The ESR pattern was observed nearly undiminished for more than three months after the irradiation. The g factor was found to be only very slightly anisotropic with an average value of 2.0124. The hyperfine interaction tensors of the unpaired electron with the two H nuclei have been determined.

Electron spin resonance of spin-trapped radicals of amines and polyamines. Hydroxyl radical reactions in aqueous solutions and γ-radiolysis in the solid state

1982 ◽  
Vol 60 (12) ◽  
pp. 1493-1500 ◽  
Author(s):  
Magdi M. Mossoba ◽  
Ionel Rosenthal ◽  
Peter Riesz
Keyword(s):  
Aqueous Solutions ◽  
Hydroxyl Radicals ◽  
Room Temperature ◽  
Spin Trap ◽  
Alkyl Chain ◽  
Spin Trapping ◽  
Radical Reactions ◽  
Hydrogen Atoms ◽  
Protonated Amino Group ◽  
Spin Resonance

The reactions of hydroxyl radicals with methylamine, dimethylamine, trimethylamine, diethylamine, sec-butylamine, ethylenediamine, 1,3-diaminopropane, putrescine, cadaverine, 1,7-diaminoheptane, ornithine, spermidine, spermine, agmatine, and arcaine in aqueous solutions have been investigated by spin-trapping and esr. Hydroxyl radicals were generated by the uv photolysis of H2O2 and 2-methyl-2-nitrosopropane (MNP) was used as the spin-trap. The effects of ionizing radiation on the same polyamines in the polycrystalline state were also investigated. The free radicals produced by γ-radiolysis of these solids at room temperature in the absence of air were identified by dissolution in aqueous solutions of MNP. The predominant reaction of [Formula: see text] with amines and polyamines below pH 7 was the abstraction of hydrogen atoms from a carbon that is not adjacent to the protonated amino group. For agmatine and arcaine which contain guanidinium groups abstraction occurred from the α-CH. Dimethylamine was oxidized to the dimethylnitroxyl radical by H2O2 in the dark. γ-Radiolysis of polyamines in the polycrystalline state generated radicals due to H-abstraction from either the α-CH or from a carbon atom in the middle of the alkyl chain. The deamination radical was obtained from ornithine.

scholarly journals Structural and Enhanced Optical Properties of Stabilized γ‒Bi2O3 Nanoparticles: Effect of Oxygen Ion Vacancies

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1023 ◽  
Author(s):  
Ashish Chhaganlal Gandhi ◽  
Chia-Liang Cheng ◽  
Sheng Yun Wu
Keyword(s):  
Room Temperature ◽  
Excess Oxygen ◽  
Ambient Atmosphere ◽  
Photoluminescence Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Band Emission ◽  
Oxygen Ion ◽  
Integrated Intensity ◽  
Effect Of Oxygen

We report the synthesis of room temperature (RT) stabilized γ–Bi2O3 nanoparticles (NPs) at the expense of metallic Bi NPs through annealing in an ambient atmosphere. RT stability of the metastable γ–Bi2O3 NPs is confirmed using synchrotron radiation powder X-ray diffraction and Raman spectroscopy. γ–Bi2O3 NPs exhibited a strong red-band emission peaking at ~701 nm, covering 81% integrated intensity of photoluminescence spectra. Our findings suggest that the RT stabilization and enhanced red-band emission of γ‒Bi2O3 is mediated by excess oxygen ion vacancies generated at the octahedral O(2) sites during the annealing process.

scholarly journals Force detection of high-frequency electron spin resonance near room temperature using high-power millimeter-wave source gyrotron

2021 ◽  
Vol 118 (2) ◽  
pp. 022407
Author(s):  
Hideyuki Takahashi ◽  
Yuya Ishikawa ◽  
Tsubasa Okamoto ◽  
Daiki Hachiya ◽  
Kazuki Dono ◽  
...  
Keyword(s):  
Electron Spin Resonance ◽  
Millimeter Wave ◽  
Electron Spin ◽  
High Power ◽  
High Frequency ◽  
Room Temperature ◽  
Force Detection ◽  
Wave Source ◽  
Spin Resonance ◽  
Millimeter Wave Source

An electron spin resonance study of the reactions of hydrogen atoms with halocarbons

1986 ◽  
Vol 64 (11) ◽  
pp. 2192-2195 ◽  
Author(s):  
William E. Jones ◽  
Joseph L. Ma
Keyword(s):  
Rate Constants ◽  
Gas Flow ◽  
Esr Spectroscopy ◽  
Flow System ◽  
Electron Spin Resonance Study ◽  
Absolute Rate ◽  
Hydrogen Atoms ◽  
Vinyl Halides ◽  
Spin Resonance ◽  
Spin Resonance Study

The absolute rate constants for the reaction of H atoms with methyl- and vinyl-halides have been determined using esr spectroscopy and a conventional gas flow system. The rate constants determined at 298 ± 2 K at a pressure of 0.55 Torr are methane, (1.7 ± 0.3) × 10−17; ethane, (2.3 ± 0.5) × 10−17; methylfluoride, (4 ± 3) × 10−15; methylchloride, (8 ± 2) × 10−16; methylbromide, (2.1 ± 0.6) × 10−14; vinylfluoride, (1.47 ± 0.02) × 10−13; vinylchloride, (1.66 ± 0.08) × 10−13; and vinylbromide (4.07 ± 0.73) × 10−13 in units of cm3 molecule−1 s−1.

Investigation of the Hydrogen Transport Processes in Crystalline Silicon of n-Type Conductivity

2007 ◽  
Vol 131-133 ◽  
pp. 425-430 ◽  
Author(s):  
Anis M. Saad ◽  
Oleg Velichko ◽  
Yu P. Shaman ◽  
Adam Barcz ◽  
Andrzej Misiuk ◽  
...  
Keyword(s):  
Hydrogen Concentration ◽  
Room Temperature ◽  
Crystalline Silicon ◽  
Transport Processes ◽  
Concentration Profiles ◽  
Hydrogen Transport ◽  
Hydrogen Atoms ◽  
Near Surface ◽  
Type Conductivity ◽  
Hydrogen Molecules

The silicon substrates were hydrogenated at approximately room temperature and hydrogen concentration profiles vs. depth have been measured by SIMS. Czochralski grown (CZ) wafers, both n- and p-type conductivity, were used in the experiments under consideration. For analysis of hydrogen transport processes and quasichemical reactions the model of hydrogen atoms diffusion and quasichemical reactions is proposed and the set of equations is obtained. The developed model takes into account the formation of bound hydrogen in the near surface region, hydrogen transport as a result of diffusion of hydrogen molecules 2 H , diffusion of metastable complexes * 2 H and diffusion of nonequilibrium hydrogen atoms. Interaction of 2 H with oxygen atoms and formation of immobile complexes “oxygen atom - hydrogen molecule” (O - H2 ) is also taken into account to explain the hydrogen concentration profiles in the substrates of n-type conductivity. The computer simulation based on the proposed equations has shown a good agreement of the calculated hydrogen profiles with the experimental data and has allowed receiving a value of the hydrogen molecules diffusivity at room temperature.

Electron spin resonance detection of heterogeneous reactions of Pigment Red 122

1990 ◽  
Vol 68 (4) ◽  
pp. 640-643
Author(s):  
Mary Jane Walzak ◽  
John R. Harbour
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Radical Anion ◽  
Heterogeneous Reactions ◽  
Resonance Spectroscopy ◽  
G Factor ◽  
Spin Resonance ◽  
Two Component ◽  
Induced Signal ◽  
Resonance Detection

Electron spin resonance spectroscopy (ESR) has been used to investigate the electrochemical and photolytic behaviour of particulate C.I. Pigment Red 122. Heterogeneous electrochemical reduction and oxidation of the pigment resulted in different reversible ESR signals with the radical cation giving a signal of ΔHpp = 2.3 G and g-factor of 2.0033 and the radical anion giving ΔHpp = 3.2 G and g-factor 2.0039. On exposure to light the inherent ESR signal, which was determined to be a two-component signal, increased in intensity by a factor of 2.4 but did not change in linewidth or g-factor. This light-induced signal was reversible and decayed to initial levels in the dark. The mechanism of these reactions is discussed. Keywords: ESR, pigment, electrochemistry, photo effects.

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