The X-ray photoelectron spectroscopy of ancient murals in the tombs at Beni Hasan, Egypt

1987 ◽  
Vol 65 (5) ◽  
pp. 1058-1064 ◽  
Author(s):  
K. M. Wilson-Yang ◽  
George Burns
Keyword(s):  
Photoelectron Spectroscopy ◽  
Archaeological Site ◽  
Photoelectron Spectra ◽  
Surface Layers ◽  
X Ray ◽  
The Past ◽  
Mural Paintings ◽  
Adsorption Of Water ◽  
Aluminium Silicates ◽  
Trace Components

The once colourful mural paintings at the Beni Hasan tombs (ca. 2100 B.C.), an important Egyptian archaeological site, are covered with an obscuring grey deposit. Qualitative observations made over the past 150 years were assembled and correlated with each other by us. Cumulatively, they indicate that recently the development of this layer has accelerated. To study this surface degradation, X-ray photoelectron spectra of fragments from the painted walls have been collected. Empirical XPS sensitivity factors have been employed to treat the data semiquantitatively. Three types of surfaces were identified. The first surface consists of CaCO3 and SiO2 as major constituents, and was the only surface identified previously. Our XPS data indicate that it also contains Al2O3, NaCl, MgO, sulphates, and phosphates as minor and trace components. The second surface consists predominantly of aluminium silicates. The third surface consists mostly of calcium carbonate. A preliminary mechanism for opaque layer formation is proposed herein. It suggests that the principal physicochemical processes are adsorption of water in the presence of carbon dioxide, followed by dissolution of the substrate walls upon which the murals were painted. This mechanism is consistent with our finding that mural deterioration is recent; it also indicates that deterioration is progressive, continuous, and cumulative. Further experiments are designed to verify the proposed mechanism. Two mechanisms proposed earlier are found to be inconsistent with at least some of our findings. Relatively recent efforts in removing obtrusive surface layers with dilute HCl were found to be performed carefully; there was no evidence of excess chlorides on cleaned surfaces. However, this finding does not provide a guarantee that murals were undamaged by HCl below the surface. It does suggest that progressive damage due to the formation of hygroscopic CaCl2 on the surface has been avoided.

X-Ray Photoelectron Spectroscopic Studies of Palladium Dispersed on Carbon Surfaces Modified by Ion Beams and Plasmatic Oxidation

1995 ◽  
Vol 60 (3) ◽  
pp. 383-392 ◽  
Author(s):  
Zdeněk Bastl
Keyword(s):  
Binding Energy ◽  
Photoelectron Spectroscopy ◽  
Surface Coverage ◽  
Spectroscopic Studies ◽  
Core Level ◽  
Graphite Surface ◽  
Photoelectron Spectra ◽  
Surface Layers ◽  
X Ray ◽  
Core Level Binding Energy

The effects of ion bombardment and r.f. plasma oxidation of graphite surfaces on subsequent growth and electronic properties of vacuum deposited palladium clusters have been investigated by methods of X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy with X-ray excitation (XAES). Due to the significantly increased density of surface defects on which the nucleation process occurs the bulk value of the Pd 3d core level binding energy is achieved at higher surface coverage by palladium on bombarded surfaces than on ordered graphite. Angle resolved photoelectron spectra of oxidized graphite surfaces reveal significant embedding of oxygen in graphite surface layers. The C 1s and O 1s photoelectron spectra are consistent with presence of two major oxygen species involving C-O and C=O type linkages which are not homogeneously distributed within the graphite surface layers. Two effects were observed on oxidized surfaces: an increase of palladium dispersion and interaction of the metal clusters with surface oxygen groups. Using the simple interpretation of the modified Auger parameter the relaxation and chemical shift contributions to the measured Pd core level shifts are estimated. In the region of low surface coverage by palladium the effect of palladium-oxygen interaction on Pd core level binding energy exceeds the effects of increased dispersity.

X-ray Photoelectron Spectroscopy of Surface Layers of Faceted Zinc Oxide Nanorods

2021 ◽  
Vol 26 (6) ◽  
pp. 481-490
Author(s):  
Z.V. Shomakhov ◽  
◽  
S.S. Nalimova ◽  
A.A. Bobkov ◽  
V.A. Moshnikov ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Binding Energy ◽  
Photoelectron Spectroscopy ◽  
Photoelectron Spectra ◽  
Zinc Oxide Nanorods ◽  
Hydroxyl Groups ◽  
Surface Layers ◽  
Defective Structure ◽  
X Ray ◽  
Oxide Nanorods

The control of the nanomaterials surface’s hydrophilic properties is of interest for various applications, including optics, photocatalysis, and spintronics. In this work, techniques for designing the defective structure of the surface layers of faceted zinc oxide nanorods during sacrificial doping with iodine by hydrothermal synthesis were considered. The features of the chemical composition of the surface of the obtained layers were studied using X-ray photoelectron spectroscopy (XPS). It was found that peaks corresponding to the binding energy of iodine were not observed in the X-ray photoelectron spectra. An additional peak with a binding energy of 531.8 eV, corresponding to the oxygen of OH groups, was observed in the O 1s level spectrum for zinc oxide nanorods doped with iodine. During the heat treatment of the synthesized layers, iodine evaporates, which leads to a change in the surface composition and an increase in the oxygen content of the surface hydroxyl groups. A model has been proposed to explain the experimental results. It has been established that XPS techniques are effective for analyzing the defective surface structure of functional layers based on faceted zinc oxide nanorods.

scholarly journals Modification of Wood with Monoethanolamino-borate by The Data of X-Ray Photoelectron Spectroscopy

2018 ◽  
Vol 196 ◽  
pp. 04005
Author(s):  
Irina Stepina ◽  
Irina Kotlyarova
Keyword(s):  
Particle Size ◽  
Photoelectron Spectroscopy ◽  
Model Compound ◽  
Hydrolytic Stability ◽  
Photoelectron Spectra ◽  
Wood Cellulose ◽  
Rapid Loss ◽  
X Ray ◽  
Wood Protection ◽  
Cellulose Materials

The difficulty of wood protection from biocorrosion and fire is due to the fact that modifiers in use are washed out from the surface of the substrate under the influence of environmental factors. This results in a rapid loss of the protective effect and other practically important wood characteristics caused by the modification. To solve this problem is the aim of our work. Here, monoethanolaminoborate is used as a modifier, where electron-donating nitrogen atom provides a coordination number equal to four to a boron atom, which determines the hydrolytic stability of the compounds formed. Alpha-cellulose ground mechanically to a particle size of 1 mm at most was used as a model compound for the modification. X-ray photoelectron spectra were recorded on the XSAM-800 spectrometer (Kratos, UK). Prolonged extraction of the modified samples preceded the registration of the photoelectron spectra to exclude the fixation of the modifier molecules unreacted with cellulose. As a result of the experiment, boron and nitrogen atoms were found in the modified substrate, which indicated the hydrolytic stability of the bonds formed between the modifier molecules and the substrate. Therefore monoethanolaminoborate can be considered as a non-extractable modifier for wood-cellulose materials.

scholarly journals Impact of high temperatures on aluminoceladonite studied by Mössbauer, Raman, X-ray diffraction and X-ray photoelectron spectroscopy

2021 ◽  
Author(s):  
Mariola Kądziołka-Gaweł ◽  
Maria Czaja ◽  
Mateusz Dulski ◽  
Tomasz Krzykawski ◽  
Magdalena Szubka
Keyword(s):  
Photoelectron Spectroscopy ◽  
Integral Intensity ◽  
Photoelectron Spectra ◽  
X Ray Diffraction ◽  
Structural Reorganization ◽  
Oh Groups ◽  
X Ray ◽  
Al Content ◽  
Integral Intensity Ratio ◽  
Higher Temperature

AbstractMössbauer, Raman, X-ray diffraction and X-ray photoelectron spectroscopies were used to examine the effects of temperature on the structure of two aluminoceladonite samples. The process of oxidation of Fe2+ to Fe3+ ions started at about 350 °C for the sample richer in Al and at 300 °C for the sample somewhat lower Al-content. Mössbauer results show that this process may be associated with dehydroxylation or even initiate it. The first stage of dehydroxylation takes place at a temperature > 350 °C when the adjacent OH groups are replaced with a single residual oxygen atom. Up to ~500 °C, Fe ions do not migrate from cis-octahedra to trans-octahedra sites, but the coordination number of polyhedra changes from six to five. This temperature can be treated as the second stage of dehydroxylation. The temperature dependence on the integral intensity ratio between bands centered at ~590 and 705 cm−1 (I590/I705) clearly reflects the temperature at which six-coordinated polyhedra are transformed into five-coordinated polyhedra. X-ray photoelectron spectra obtained in the region of the Si2p, Al2p, Fe2p, K2p and O1s core levels, highlighted a route to identify the position of Si, Al, K and Fe cations in a structure of layered silicates with temperature. All the measurements show that the sample with a higher aluminum content and a lower iron content in octahedral sites starts to undergo a structural reorganization at a relatively higher temperature than the less aluminum-rich sample does. This suggests that iron may perform an important role in the initiation of the dehydroxylation of aluminoceladonites.

scholarly journals Characterization of Ti/SnO2 Interface by X-ray Photoelectron Spectroscopy

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 202
Author(s):  
Miranda Martinez ◽  
Anil R. Chourasia
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Chemical Interaction ◽  
Photoelectron Spectra ◽  
X Ray ◽  
Increasing Trend ◽  
Substrate Temperatures ◽  
Beam Technique

The Ti/SnO2 interface has been investigated in situ via the technique of x-ray photoelectron spectroscopy. Thin films (in the range from 0.3 to 1.1 nm) of titanium were deposited on SnO2 substrates via the e-beam technique. The deposition was carried out at two different substrate temperatures, namely room temperature and 200 °C. The photoelectron spectra of tin and titanium in the samples were found to exhibit significant differences upon comparison with the corresponding elemental and the oxide spectra. These changes result from chemical interaction between SnO2 and the titanium overlayer at the interface. The SnO2 was observed to be reduced to elemental tin while the titanium overlayer was observed to become oxidized. Complete reduction of SnO2 to elemental tin did not occur even for the lowest thickness of the titanium overlayer. The interfaces in both the types of the samples were observed to consist of elemental Sn, SnO2, elemental titanium, TiO2, and Ti-suboxide. The relative percentages of the constituents at the interface have been estimated by curve fitting the spectral data with the corresponding elemental and the oxide spectra. In the 200 °C samples, thermal diffusion of the titanium overlayer was observed. This resulted in the complete oxidation of the titanium overlayer to TiO2 upto a thickness of 0.9 nm of the overlayer. Elemental titanium resulting from the unreacted overlayer was observed to be more in the room temperature samples. The room temperature samples showed variation around 20% for the Ti-suboxide while an increasing trend was observed in the 200 °C samples.

X-Ray photoelectron spectroscopy of monosubstituted perfluorobenzenes

1977 ◽  
Vol 55 (8) ◽  
pp. 1279-1284 ◽  
Author(s):  
Barry C. Trudell ◽  
S. James W. Price
Keyword(s):  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Atomic Charges ◽  
X Ray ◽  
Sophisticated Analysis ◽  
Charge Calculations

The gas phase X-ray photoelectron spectra, XPS, were observed for the series C6F5X (X = F, Cl, I, Br, H). Binding energies were determined from the spectra using the ESCAPLOT Program. Charge calculations were carried out using Equalization of Electronegativity, CNDO/2, and ACHARGE approaches on each molecule. The more sophisticated analysis leads to the following equation correlating the (C 1s) binding energies and the atomic charges qi[Formula: see text]

X-ray photoelectron spectroscopic analysis of halloysites with different composition and particle morphology

Clay Minerals ◽  
1992 ◽  
Vol 27 (4) ◽  
pp. 413-421 ◽  
Author(s):  
M. Soma ◽  
G. J. Churchman ◽  
B. K. G. Theng
Keyword(s):  
Photoelectron Spectroscopy ◽  
Cation Exchange Capacity ◽  
Spectroscopic Analysis ◽  
Surface Composition ◽  
Particle Morphology ◽  
Exchange Capacity ◽  
Surface Layers ◽  
X Ray ◽  
Fe Content ◽  
Before And After

AbstractThe surface composition of some halloysites with different particle morphology has been investigated by X-ray photoelectron spectroscopy (XPS) before and after removal of external Fe. The Fe(III) 2p3/2 binding energy of external Fe is appreciably smaller than that of structural Fe. Particle morphology is influenced by structural Fe content. The long-tubular halloysite has very little surface Fe, and its concentration tends to increase with the proportion of non-tubular particles in the samples. The spheroidal sample contains the most structural Fe which, however, does not appear to influence particle shape directly. Study by XPS indicates that Fe substitutes for Al in octahedral positions in approximately 1 : 2 proportion. As a result, an increase in octahedral vacancies and cation exchange capacity would be predicted. Further, halloysite layers within a crystal are generally inhomogeneous in composition. Built up like “onion skins”, the surface layers would either be enriched or depleted in Fe depending on the chemical environment in which crystal growth occurs.

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