Recombination of atoms on surfaces. Part 13.—Oxygen atoms on ZnxFe3–xO4and NixFe3–xO4

1971 ◽  
Vol 67 (0) ◽  
pp. 191-197 ◽  
Author(s):  
J. W. Linnett ◽  
M. M. Rahman
Keyword(s):  
Oxygen Atoms

Catalytic CO Oxidation on Unreconstructed Cu(110) by Reactive As-Adsorbed Oxygen Atoms below 230 K

1996 ◽  
Vol 100 (3) ◽  
pp. 1048-1054 ◽  
Author(s):  
Tsuyoshi Sueyoshi ◽  
Takehiko Sasaki ◽  
Yasuhiro Iwasawa
Keyword(s):  
Co Oxidation ◽  
Adsorbed Oxygen ◽  
Catalytic Co Oxidation ◽  
Oxygen Atoms

Modification of optical properties of PC-PBT/Cr2O3 and PC-PBT/CdS nanocomposites by gamma irradiation

2020 ◽  
Vol 92 (2) ◽  
pp. 20402
Author(s):  
Kaoutar Benthami ◽  
Mai ME. Barakat ◽  
Samir A. Nouh
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Color Difference ◽  
Band Gap Energy ◽  
Polybutylene Terephthalate ◽  
Γ Irradiation ◽  
Gap Energy ◽  
Vis Spectroscopy ◽  
Oxygen Atoms

Nanocomposite (NCP) films of polycarbonate-polybutylene terephthalate (PC-PBT) blend as a host material to Cr2O3 and CdS nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Samples from the PC-PBT/Cr2O3 and PC-PBT/CdS NCPs were irradiated using different doses (20–110 kGy) of γ radiation. The induced modifications in the optical properties of the γ irradiated NCPs have been studied as a function of γ dose using UV Vis spectroscopy and CIE color difference method. Optical dielectric loss and Tauc's model were used to estimate the optical band gaps of the NCP films and to identify the types of electronic transition. The value of optical band gap energy of PC-PBT/Cr2O3 NCP was reduced from 3.23 to 3.06 upon γ irradiation up to 110 kGy, while it decreased from 4.26 to 4.14 eV for PC-PBT/CdS NCP, indicating the growth of disordered phase in both NCPs. This was accompanied by a rise in the refractive index for both the PC-PBT/Cr2O3 and PC-PBT/CdS NCP films, leading to an enhancement in their isotropic nature. The Cr2O3 NPs were found to be more effective in changing the band gap energy and refractive index due to the presence of excess oxygen atoms that help with the oxygen atoms of the carbonyl group in increasing the chance of covalent bonds formation between the NPs and the PC-PBT blend. Moreover, the color intensity, ΔE has been computed; results show that both the two synthesized NCPs have a response to color alteration by γ irradiation, but the PC-PBT/Cr2O3 has a more response since the values of ΔE achieved a significant color difference >5 which is an acceptable match in commercial reproduction on printing presses. According to the resulting enhancement in the optical characteristics of the developed NCPs, they can be a suitable candidate as activate materials in optoelectronic devices, or shielding sheets for solar cells.

Tandem Mass Spectrometric Evaluation of Core Structures of Aromatic Compounds after Catalytic Deoxygenation

2017 ◽  
Author(s):  
Xueming Dong
Keyword(s):  
Aromatic Compounds ◽  
Supported Catalyst ◽  
Mass Spectrometric ◽  
Spectrometric Method ◽  
Mass Spectrometric Method ◽  
Aromatic Rings ◽  
Tandem Mass Spectrometric ◽  
Catalytic Deoxygenation ◽  
Oxygen Atoms

Catalytic deoxygenation of coal enhances the stability and combustion performance of coal-derived liquids. However, determination of the selectivity of removal of oxygen atoms incorporated in or residing outside of aromatic rings is challenging. This limits the ability to evaluate the success of catalytic deoxygenation processes. A mass spectrometric method, in-source collision-activated dissociation (ISCAD), combined with high resolution product ion detection, is demonstrated to allow the determination of whether the oxygen atoms in aromatic compounds reside outside of aromatic rings or are part of the aromatic system, because alkyl chains can be removed from aromatic cores via ISCAD. Application of this method for the analysis of a subbituminous coal treated using a supported catalyst revealed that the catalytic treatment reduced the number of oxygen-containing heteroaromatic rings but not the number of oxygen atoms residing outside the aromatic rings.<br>

Tandem Mass Spectrometric Evaluation of Core Structures of Aromatic Compounds after Catalytic Deoxygenation

2017 ◽  
Author(s):  
Xueming Dong
Keyword(s):  
Aromatic Compounds ◽  
Supported Catalyst ◽  
Mass Spectrometric ◽  
Spectrometric Method ◽  
Mass Spectrometric Method ◽  
Aromatic Rings ◽  
Tandem Mass Spectrometric ◽  
Catalytic Deoxygenation ◽  
Oxygen Atoms

Catalytic deoxygenation of coal enhances the stability and combustion performance of coal-derived liquids. However, determination of the selectivity of removal of oxygen atoms incorporated in or residing outside of aromatic rings is challenging. This limits the ability to evaluate the success of catalytic deoxygenation processes. A mass spectrometric method, in-source collision-activated dissociation (ISCAD), combined with high resolution product ion detection, is demonstrated to allow the determination of whether the oxygen atoms in aromatic compounds reside outside of aromatic rings or are part of the aromatic system, because alkyl chains can be removed from aromatic cores via ISCAD. Application of this method for the analysis of a subbituminous coal treated using a supported catalyst revealed that the catalytic treatment reduced the number of oxygen-containing heteroaromatic rings but not the number of oxygen atoms residing outside the aromatic rings.<br>

Tuning the Activities of Cu2O Nanostructures via the Oxide-Metal Interaction

2019 ◽  
Author(s):  
Wugen Huang ◽  
qingfei liu ◽  
Zhiwen Zhou ◽  
Yangsheng Li ◽  
Yong Wang ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Oxidation Catalysis ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Oxidation Reactions ◽  
Tunneling Microscopy ◽  
Temperature Oxidation ◽  
Metal Interaction ◽  
Tremendous Importance ◽  
Oxygen Atoms

Despite tremendous importance in catalysis, the design and improvement of the oxide- metal interface has been hampered by the limited understanding on the nature of interfacial sites, as well as the oxide-metal interaction (OMI). Through the construction of well-defined Cu<sub>2</sub>O-Pt, Cu<sub>2</sub>O-Ag, Cu<sub>2</sub>O-Au interfaces, we found that Cu<sub>2</sub>O Nanostructures (NSs) on Pt exhibit much lower thermal stability than on Ag and Au, although they show the same surface and edge structures, as identified by element-specific scanning tunneling microscopy (ES-STM) images. The activities of the Cu<sub>2</sub>O-Pt and Cu<sub>2</sub>O-Au interfaces for CO oxidation were further compared at the atomic scale and showed in general that the interface with Cu<sub>2</sub>O NSs could annihilate the CO-poisoning problem suffered by Pt group metals and enhance the interaction with O<sub>2</sub>, which is a limiting step for CO oxidation catalysis on group IB metals. While both interfaces could react with CO at room temperature, the OMI was found to determine the reactivity of supported Cu<sub>2</sub>O NSs by 1) tuning the activity of interfacial oxygen atoms and 2) stabilizing oxygen vacancies or vice versa, the dissociated oxygen atoms at the interface. Our study provides new insight for OMI and for the development of Cu-based catalysts for low temperature oxidation reactions.

Tuning the Activities of Cu2O Nanostructures via the Oxide-Metal Interaction

2019 ◽  
Author(s):  
Wugen Huang ◽  
Yangsheng Li ◽  
Yong Wang ◽  
Yunchuan Tu ◽  
Dehui Deng ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Oxidation Catalysis ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Oxidation Reactions ◽  
Tunneling Microscopy ◽  
Temperature Oxidation ◽  
Metal Interaction ◽  
Tremendous Importance ◽  
Oxygen Atoms

Despite tremendous importance in catalysis, the design and improvement of the oxide- metal interface has been hampered by the limited understanding on the nature of interfacial sites, as well as the oxide-metal interaction (OMI). Through the construction of well-defined Cu<sub>2</sub>O-Pt, Cu<sub>2</sub>O-Ag, Cu<sub>2</sub>O-Au interfaces, we found that Cu<sub>2</sub>O Nanostructures (NSs) on Pt exhibit much lower thermal stability than on Ag and Au, although they show the same surface and edge structures, as identified by element-specific scanning tunneling microscopy (ES-STM) images. The activities of the Cu<sub>2</sub>O-Pt and Cu<sub>2</sub>O-Au interfaces for CO oxidation were further compared at the atomic scale and showed in general that the interface with Cu<sub>2</sub>O NSs could annihilate the CO-poisoning problem suffered by Pt group metals and enhance the interaction with O<sub>2</sub>, which is a limiting step for CO oxidation catalysis on group IB metals. While both interfaces could react with CO at room temperature, the OMI was found to determine the reactivity of supported Cu<sub>2</sub>O NSs by 1) tuning the activity of interfacial oxygen atoms and 2) stabilizing oxygen vacancies or vice versa, the dissociated oxygen atoms at the interface. Our study provides new insight for OMI and for the development of Cu-based catalysts for low temperature oxidation reactions.

EXPERIMENTAL STUDY OF REACTION OF ETHANOL WITH OXYGEN BEHIND SHOCK WAVES USING ATOMIC RESONANCE ABSORPTION SPECTROSCOPY METHOD

2020 ◽  
Author(s):  
N. S. Bystrov ◽  
◽  
A. V. Emelianov ◽  
A. V. Eremin ◽  
P. I. Yatsenko ◽  
...  
Keyword(s):  
Experimental Study ◽  
Shock Waves ◽  
Absorption Spectroscopy ◽  
Vacuum Ultraviolet ◽  
Resonance Absorption ◽  
Atomic Resonance ◽  
Quantitative Measurements ◽  
Series Of Experiments ◽  
Kinetics Of Reaction ◽  
Oxygen Atoms

The kinetics of reaction of C2H5OH with N2O behind shock waves is studied. The quantitative measurements of the time profiles of concentration of O atoms were carried out by the method of atomic resonance absorption spectroscopy (ARAS) using resonance vacuum-ultraviolet line of O-atom at 130.5 nm. For the calibration of absorption intensity of oxygen atoms depending on its concentration, the special series of experiments in the mixture containing different amounts of N2O in Ar was carried out at T = 2100 ± 50 K when molecule of N2O is completely dissociated. An experimental study of the appearance and consumption of oxygen atoms during the reaction of ethanol with oxygen in mixture 10 ppm N2O + (10 ... 0.1) ppm C2H5OH + Ar at temperatures of 16002300 K and pressures of 200-300 kPa have been carried out. A kinetic analysis of obtained data was performed using the Chemkin package.

17O and 13C NMR spectra of some geminal diacetates

1988 ◽  
Vol 53 (3) ◽  
pp. 588-592 ◽  
Author(s):  
Antonín Lyčka ◽  
Josef Jirman ◽  
Jaroslav Holeček
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
The Other ◽  
13C Nmr Spectra ◽  
Other Hand ◽  
Carboxylic Esters ◽  
C Nmr ◽  
Oxygen Atoms

The 17O and 13C NMR spectra of eight geminal diacetates RCH(O(CO)CH3)2 derived from simple aldehydes have been measured. In contrast to the dicarboxylates R1R2E(O(CO)R3)2, where E = Si, Ge, or Sn, whose 17O NMR spectra only contain a single signal, and, on the other hand, in accordance with organic carboxylic esters, the 17O NMR spectra of the compound group studied always exhibit two well-resolved signals with the chemical shifts δ(17O) in the regions of 183-219 ppm and 369-381 ppm for the oxygen atoms in the groups C-O and C=O, respectively.

17O, 13C, and 29Si NMR spectra of some acyloxy- and diacetoxysilanes and acetoxygermanes

1986 ◽  
Vol 51 (11) ◽  
pp. 2582-2589 ◽  
Author(s):  
Antonín Lyčka ◽  
Jaroslav Holeček ◽  
Karel Handlíř ◽  
Josef Pola ◽  
Václav Chvalovský
Keyword(s):  
Periodic System ◽  
Time Scale ◽  
Nmr Spectra ◽  
Group Element ◽  
29Si Nmr ◽  
Carboxyl Group ◽  
29Si Nmr Spectra ◽  
Oxygen Atoms

The 17O, 13C, and 29Si NMR spectra of (CH3)3SiOC(O)R, CH3(XCH2)Si(OC(O)CH3)2, and R3GeOC(O)CH3 compounds are reported. In the 17O NMR spectra at 350 K the only signal is observed with the two latter series, but two well-resolved signals are displayed with the (CH3)3SiOC(O)R compounds. The equivalence of both oxygen atoms in carboxyl group on the NMR time scale is discussed from the viewpoint of a possible coordination of the oxygen atoms to the IVB group element of the periodic system.

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