scholarly journals Following excited-state chemical shifts in molecular ultrafast x-ray photoelectron spectroscopy

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
D. Mayer ◽  
F. Lever ◽  
D. Picconi ◽  
J. Metje ◽  
S. Alisauskas ◽  
...  
Keyword(s):  
Excited State ◽  
Chemical Shift ◽  
Photoelectron Spectroscopy ◽  
Chemical Shifts ◽  
Excited Molecule ◽  
Charge Motion ◽  
Core Electron ◽  
Xps Spectra ◽  
X Ray ◽  
State Chemical

AbstractThe conversion of photon energy into other energetic forms in molecules is accompanied by charge moving on ultrafast timescales. We directly observe the charge motion at a specific site in an electronically excited molecule using time-resolved x-ray photoelectron spectroscopy (TR-XPS). We extend the concept of static chemical shift from conventional XPS by the excited-state chemical shift (ESCS), which is connected to the charge in the framework of a potential model. This allows us to invert TR-XPS spectra to the dynamic charge at a specific atom. We demonstrate the power of TR-XPS by using sulphur 2p-core-electron-emission probing to study the UV-excited dynamics of 2-thiouracil. The method allows us to discover that a major part of the population relaxes to the molecular ground state within 220–250 fs. In addition, a 250-fs oscillation, visible in the kinetic energy of the TR-XPS, reveals a coherent exchange of population among electronic states.

scholarly journals XPS Investigations on Solid and Vacuum Deposited, Oxidized and Non-oxidized Palladium

1995 ◽  
Vol 50 (4-5) ◽  
pp. 381-387 ◽  
Author(s):  
Jürgen Kintrup ◽  
Harald Züchner
Keyword(s):  
Chemical Shift ◽  
Curve Fitting ◽  
Photoelectron Spectroscopy ◽  
Chemical Shifts ◽  
Atmospheric Oxygen ◽  
Hydrogen Permeability ◽  
Photoelectric Effect ◽  
High Accuracy ◽  
X Ray ◽  
Charging Effect

Abstract X-ray photoelectron spectroscopy (XPS) has been carried out to study the reaction of differently prepared palladium samples (solid and film Pd) with atmospheric oxygen. A careful curve fitting of the measured Pd-3d5/2 peak allows to separate the Pd-3d5/2 peak for Pd in surface PdO from the dominant Pd-3d5/2 peak of the non-oxidized bulk palladium and to determine the chemical shift of the "oxidized" Pa line with high accuracy. Differences in the chemical shifts for the surface PdO on solid and film palladium are explained by a different charging caused by the photoelectric effect in XPS measurements. The smaller charging effect observed for film palladium as compared to solid palladium indicates a stronger oxygen bonding to the (rougher) film palladium. The strong Pd-O bonding seems to be an essential reason for the reduced hydrogen-permeability of film palladium compared to solid palladium

CHEMISORPTION OF L-CYSTEINE ON Au(111)/Si(111) AND $Si(111)\sqrt{3} \times \sqrt{3}-{\rm Au}$ SURFACES

2006 ◽  
Vol 13 (02n03) ◽  
pp. 197-200 ◽  
Author(s):  
MITSUNORI HONDA ◽  
FUMIHIKO MATSUI ◽  
HIROSHI DAIMON
Keyword(s):  
Chemical Shift ◽  
Photoelectron Spectroscopy ◽  
Electronic Structures ◽  
The Other ◽  
Cooh Group ◽  
Xps Spectra ◽  
X Ray ◽  
Peak Intensity ◽  
Before And After ◽  
Intensity Ratios

The electronic structures of L-cysteine adsorbed on Au (111)/ Si (111) and [Formula: see text] surfaces were studied by using X-ray photoelectron spectroscopy (XPS). L-cysteine multilayers on Au (111)/ Si (111) and [Formula: see text] surfaces were prepared under UHV condition. L-cysteine monolayers were obtained by annealing such multilayer sample up to 130°C. In the case of the Au (111)/ Si (111) surface, we observed no chemical shift and no change in the peak intensity ratios among C1s , N1s , O1s and S 2p before and after annealing. On the other hand, the component attributed to COOH group in C1s spectra decreased after annealing. In addition, O1s XPS spectra of monolayer on the [Formula: see text] surface was composed of two distinct peaks, which indicates that there are two kinds of O atoms in different conformations. These observations indicate that the COOH group adsorbs directly to a surface atoms and dissociate by the interaction with the substrate Si (111) trimer atoms.

scholarly journals Optical, XPS and XRD Studies of Semiconducting Copper Sulfide Layers on a Polyamide Film

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
Valentina Krylova ◽  
Mindaugas Andrulevičius
Keyword(s):  
Photoelectron Spectroscopy ◽  
Copper Sulfide ◽  
Diffusion Method ◽  
X Ray Diffraction ◽  
Xps Spectra ◽  
X Ray ◽  
Xrd Studies ◽  
Polyamide Film ◽  
Indirect Band Gap ◽  
Xrd Method

Copper sulfide layers were formed on polyamide PA 6 surface using the sorption-diffusion method. Polymer samples were immersed for 4 and 5 h in 0.15 mol⋅  solutions and acidified with HCl (0.1 mol⋅) at . After washing and drying, the samples were treated with Cu(I) salt solution. The samples were studied by UV/VIS, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) methods. All methods confirmed that on the surface of the polyamide film a layer of copper sulfide was formed. The copper sulfide layers are indirect band-gap semiconductors. The values of are 1.25 and 1.3 eV for 4 h and 5 h sulfured PA 6 respectively. Copper XPS spectra analyses showed Cu(I) bonds only in deeper layers of the formed film, while in sulfur XPS S 2p spectra dominating sulfide bonds were found after cleaning the surface with ions. It has been established by the XRD method that, beside , the layer contains as well. For PA 6 initially sulfured 4 h, grain size forchalcocite, , was  nm and fordjurleite, , it was 54.17 nm. The sheet resistance of the obtained layer varies from 6300 to 102 .

29Si NMR and XPS Investigation of the Structure of Silicon Oxycarbide Glasses Derived from Polysiloxane Precursors

1994 ◽  
Vol 346 ◽  
Author(s):  
R.J.P. Corriu ◽  
D. Leclercq ◽  
P.H. Mutin ◽  
A. Vioux
Keyword(s):  
Solid State ◽  
Photoelectron Spectroscopy ◽  
Solid State Nmr ◽  
Random Distribution ◽  
Silicon Oxycarbide ◽  
29Si Nmr ◽  
Xps Spectra ◽  
Excess Carbon ◽  
X Ray ◽  
Silicon Oxycarbide Glasses

ABSTRACTTwo silicon oxycarbide glasses with different compositions (O/Si ratio 1.2 and 1.8) were prepared by pyrolysis at moderate temperature (900 °C) of polysiloxane precursors. Their structure was investigated using quantitative 29Si solid-state NMR and X-ray photoelectron spectroscopy (XPS). The environment of the silicon atoms in the oxycarbide phase corresponded to a purely random distribution of Si-O and Si-C bonds depending on the O/Si ratio of the glass only and not on the structure of the precursors. At the light of the NMR results, the Si2p XPS spectra of the glasses may be interpreted using the contribution of the five possible SiOxC4-x tetrahedra. The Cls spectra of these glasses indicated the presence of oxycarbide carbon in CSi4 tetrahedra, similar to carbide carbon, and graphitic-like excess carbon.

Preparation and Characterization of Ni2+-Montmorillonite/Polyvinyl Alcohol Water-Soluble Nanocomposite Film

2005 ◽  
Vol 13 (8) ◽  
pp. 839-846 ◽  
Author(s):  
Li-Ping Wang ◽  
Yun-Pu Wang ◽  
Fa-Ai Zhang
Keyword(s):  
Polyvinyl Alcohol ◽  
Photoelectron Spectroscopy ◽  
Thermal Characteristics ◽  
Water Soluble ◽  
Scanning Calorimetry ◽  
Xps Spectra ◽  
X Ray ◽  
Alcohol Water ◽  
Ft Ir ◽  
Silicate Layers

A new type of nano-composite film was prepared from polyvinyl alcohol, Ni2+-montmorillonite (Ni2+-MMT), defoamer, a levelling agent and a plasticizer. Its thermal characteristics were studied by Differential Scanning Calorimetry (DSC). The intermolecular interactions were measured by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), and the tensile strength (TS) and elongation at break (%E) were measured. The microstructures were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM). FT-IR and XPS spectra indicated that cross-linking has taken place between PVA and Ni2+-MMT. XRD and AFM indicate that the PVA molecules had inserted themselves into the silicate layers of MMT, exfoliating them and dispersing them randomly into the PVA matrix. Compared to pure PVA film, the TS of the films was increased and %E decreased when the Ni2+-Montmorillonite was added and the dissolution temperature of the film was also reduced.

X-ray photoelectron spectroscopy characterization of barium titanate ceramics prepared by the citric route. Residual carbon study

1997 ◽  
Vol 12 (9) ◽  
pp. 2388-2392 ◽  
Author(s):  
C. Miot ◽  
E. Husson ◽  
C. Proust ◽  
R. Erre ◽  
J. P. Coutures
Keyword(s):  
Barium Titanate ◽  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Residual Carbon ◽  
Ion Etching ◽  
Xps Spectra ◽  
X Ray ◽  
Titanate Ceramics

Powder and ceramics of barium titanate prepared by the citric process were studied by x-ray photoelectron spectroscopy (XPS). Spectra of C1s, O1s, Ti2p, Ba3d, and Ba4d levels are analyzed in powder and ceramics immediately after the sintering step and after several months of exposure in the air. Ar-ion etching allowed one to characterize the material intrinsic carbon. The results are discussed in comparison with works previously published on oxide single crystals.

Determination of the oxidation state of manganese in lepidolite by X-ray photoelectron spectroscopy

Clay Minerals ◽  
1982 ◽  
Vol 17 (4) ◽  
pp. 477-481 ◽  
Author(s):  
S. Evans ◽  
E. Raftery
Keyword(s):  
Oxidation State ◽  
Photoelectron Spectroscopy ◽  
Electronic Spectroscopy ◽  
Binding Energies ◽  
Core Electron ◽  
X Ray ◽  
Occasional Occurrence ◽  
The Subject ◽  
Electron Binding Energies

It is usually assumed that the oxidation state of the small proportion of Mn sometimes present in micas is +2, although there is evidence from electronic spectroscopy (Burns, 1970) for at least the occasional occurrence of Mn(III) in manganophyllite. We describe here X-ray photoelectron spectroscopic (XPS) measurements on the Mn in a Norwegian lepidolite which was the subject of a concurrent structural study by X-ray photoelectron diffraction (Evans & Raftery, 1982). To establish the Mn oxidation state we have compared the Mn2p core-electron binding energies (BE), the Mn2P3/2-O ls BE differences, and the Mn2p XPS peak profiles from the four common oxides of manganese (MnO, Mn3O4, Mn2O3 and MnO2) with those from the lepidolite. A re-examination of these oxides was undertaken because the agreement between reports in the literature was unsatisfactory, and uncertainty existed concerning the integrity of some of the surfaces previously examined.

scholarly journals Bacterial Compatibility/Toxicity of Biogenic Silica (b-SiO2) Nanoparticles Synthesized from Biomass Rice Husk Ash

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1440 ◽  
Author(s):  
Sanjeev K. Sharma ◽  
Ashish R. Sharma ◽  
Sudheer D. V. N. Pamidimarri ◽  
Jyotshana Gaur ◽  
Beer Pal Singh ◽  
...  
Keyword(s):  
Rice Husk ◽  
Photoelectron Spectroscopy ◽  
Biogenic Silica ◽  
Rice Husk Ash ◽  
Sio2 Nanoparticles ◽  
High Porosity ◽  
Xps Spectra ◽  
X Ray ◽  
Xrd Patterns ◽  
Sio2 Nanopowder

Biogenic silica (b-SiO2) nanopowders from rice husk ash (RHA) were prepared by chemical method and their bacterial compatibility/toxicity was analyzed. The X-ray diffractometry (XRD) patterns of the b-SiO2 nanopowders indicated an amorphous feature due to the absence of any sharp peaks. Micrographs of the b-SiO2 revealed that sticky RHA synthesized SiO2 nanopowder (S1) had clustered spherical nanoparticles (70 nm diameter), while b-SiO2 nanopowder synthesized from red RHA (S2) and b-SiO2 nanopowder synthesized from brown RHA (S3) were purely spherical (20 nm and 10 nm diameter, respectively). Compared to the S1 (11.36 m2g−1) and S2 (234.93 m2g−1) nanopowders, the S3 nanopowders showed the highest surface area (280.16 m2g−1) due to the small particle size and high porosity. The core level of the X-ray photoelectron spectroscopy (XPS) spectra showed that Si was constituted by two components, Si 2p (102.2 eV) and Si 2s (153.8 eV), while Oxygen 1s was observed at 531.8 eV, confirming the formation of SiO2. The anti-bacterial activity of the b-SiO2 nanopowders was investigated using both gram-positive (Escherichia coli) and gram-negative (Staphylococcus aureus) microorganisms. Compared to S2 and S3 silica nanopowders, S1 demonstrated enhanced antibacterial activity. This study signifies the medical, biomedical, clinical, and biological importance and application of RHA-mediated synthesized b-SiO2.

The Electronic Structures of Fullerene/Transition-Metal Hybrid Material

2008 ◽  
Vol 1081 ◽  
Author(s):  
Yoshihiro Matsumoto ◽  
Seiji Sakai ◽  
Hiroshi Naramoto ◽  
Norie Hirao ◽  
Yuji Baba ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electronic Structures ◽  
Line Broadening ◽  
Hybrid Films ◽  
Xps Spectra ◽  
X Ray ◽  
Nexafs Spectroscopy ◽  
Homo Level ◽  
Valence Band Region ◽  
X Ray Absorption

ABSTRACTLocal electronic structures of C60-Co hybrid films have been studied by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. XPS spectra of C 1s main and satellite peaks for the C60-Co films show binding-energy shifts and also line-broadening compared to those in a pure C60 film. In addition, XPS spectra in valence band region suggest an appearance of three new components at near Fermi level and HOMO level in the C60-Co film. These results are attributed to hybridizations between Co 3d band and C60 LUMO. The same effects have been observed in NEAXFS spectra at C 1s excitations.

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