scholarly journals Resonant Soft X-Ray Fluorescence Studies of Novel Materials

1994 ◽  
Vol 375 ◽  
Author(s):  
J. A. Carlisle ◽  
E. L. Shirley ◽  
L. J. Terminello ◽  
E. A. Hudson ◽  
J. J. Jia ◽  
...  
Keyword(s):  
Pyrolytic Graphite ◽  
Emission Spectra ◽  
Excited Electron ◽  
Core Electron ◽  
Emission Process ◽  
X Ray ◽  
Fluorescence Studies ◽  
Novel Materials ◽  
The Core ◽  
Resonant Emission

AbstractWe are using resonant soft x-ray fluorescence at the Advanced Light Source to probe the electronic and geometric structure of novel materials. In the resonant process, a core electron is excited by a photon whose energy is near the core binding energy. In this energy regime the absorption and emission processes are coupled, and this coupling manifests itself in several ways. In boron nitride (BN), the resonant emission spectra reflect the influence of a “spectator” electron in an unoccupied excitonic state. The resonant emission can be used to distinguish between the various bulk phases of BN, and can also be used to probe the electronic structure of a monolayer of BN buried in a bulk environment, where it is inaccessible to electron spectroscopies. For highly-oriented pyrolytic graphite (HOPG) a coherent absorption-emission process takes place in the resonant regime, whereby crystalline momentum is conserved between the core excited electron and the valence hole which remains after emission

CORE-HOLE EFFECT IN THE Ce L3 X-RAY ABSORPTION SPECTRA OF CeO2 AND CeFe2: NEW EXAMINATION BY USING RESONANT X-RAY EMISSION SPECTROSCOPY

2013 ◽  
Vol 27 (16) ◽  
pp. 1330012 ◽  
Author(s):  
A. KOTANI
Keyword(s):  
Absorption Spectra ◽  
Ground State ◽  
Theoretical Calculations ◽  
Emission Spectra ◽  
Core Hole ◽  
Final State ◽  
X Ray ◽  
The Core ◽  
X Ray Absorption ◽  
Hole Effect

We consider two different resonant X-ray emission spectra for Ce compounds: Ce 3d to 2p X-ray emission (denoted by 3d-RXES) and valence to 2p X-ray emission (v-RXES), both of which follow the Ce 2p to 5d resonant excitation. We propose that the comparison of the 3d- and v-RXES spectra is a new powerful method of directly detecting the core-hole effect in the final state of Ce L 3 X-ray absorption spectra (XAS). We applied this method to recent experimental RXES spectra for CeO 2 and CeFe 2, and showed unambiguously that the core-hole effect should be essential in the XAS of both materials. This result is confirmed by theoretical calculations, which reproduce well the experimental RXES and XAS spectra. We conclude that the ground state of CeO 2 is in the mixed state of 4f0 and [Formula: see text] configurations, where [Formula: see text] is a ligand hole, instead of a pure 4f0 configuration which was proposed recently by first-principles energy band calculations. Also, we conclude that the double peaks observed in L 3 XAS of CeFe 2 are caused by the 4f0 and 4f1 configurations, which are mixed in the ground state but separated in energy by the large core-hole potential in the final state of XAS.

Ag2S/ZnS nanocomposites: Synthesis, structure and optical properties

2020 ◽  
pp. 2150033
Author(s):  
M. A. Ramazanov ◽  
S. G. Nuriyeva ◽  
H. A. Shirinova ◽  
A. H. Karimova ◽  
M. A. Nuriyev
Keyword(s):  
Optical Properties ◽  
Structural Investigation ◽  
Emission Spectra ◽  
Structural Features ◽  
Core Shell ◽  
Zns Nanoparticles ◽  
Sem Images ◽  
X Ray ◽  
The Core ◽  
Novel Method

Ag2S/ZnS nanocomposites were synthesized using a novel method, and their structural features and optical properties were also investigated. For the structural investigation of the core/shell-like nanocomposites, X-ray powder diffraction technique (XRD) and scanning electron microscopy (SEM) were used. Optical features of Ag2S/ZnS nanocomposites were studied by UV-Vis absorption and photoluminescence spectroscopy (PL). According to the SEM images, the sizes of the Ag2S, ZnS nanoparticles and Ag2S/ZnS core/shell-like nanocomposites are in the region of the 10–15; 25–50 and 15–80 nm, respectively. Furthermore, the absorption spectroscopy indicates that the bandgap of Ag2S/ZnS nanocomposites is approximately 2.4 eV. By comparison of the intensities of the emission spectra, it was clear that the intensity of Ag2S/ZnS is much lower than that of ZnS.

X-ray photoelectron spectroscopic (XPS) studies of iodine oxocompounds

1988 ◽  
Vol 53 (3) ◽  
pp. 425-432 ◽  
Author(s):  
Zdeněk Bastl ◽  
Heidrun Gehlmann
Keyword(s):  
Cross Sections ◽  
Chemical Shifts ◽  
Theoretical Data ◽  
Binding Energies ◽  
Oxidation States ◽  
Core Electron ◽  
X Ray ◽  
The Core ◽  
Quantitative Surface Analysis ◽  
Electron Binding Energies

The core electron binding energies of eighteen compounds containing iodine in different oxidation states ranging from (-I) to (VII) have been measured. The observed chemical shifts differ from the literature data. The anticipated existence of hexavalent iodine in certain compounds has not been demonstrated. The relative subshell photoemission intensities of iodine have been determined. Empirically derived atomic sensitivity factors and theoretical photoionization cross-sections have been used to calculate the surface stoichiometry. The concentration ratios obtained via the two methods are compared. In agreement with generally accepted view the results of this comparison imply that, for quantitative surface analysis, empirical values should be used rather than theoretical data.

Narrow-Band Synchrotron Radiation Excitation of Soft X-Ray Emission Spectra

1993 ◽  
Vol 307 ◽  
Author(s):  
K. E. Miyano ◽  
W. L. O'Brien ◽  
D. L. Ederer ◽  
T. A. Callcott ◽  
J. J. Jia ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Excitation Energy ◽  
Crystalline Silicon ◽  
Narrow Band ◽  
Emission Spectra ◽  
Phonon Coupling ◽  
Excitation Energies ◽  
Final State ◽  
X Ray ◽  
The Core

ABSTRACTMonochromatized synchrotron radiation has been employed as the excitation source for soft x-ray emission spectroscopy. In the present paper changes in the emission spectra that occur as the excitation energy is varied near the core-absorption threshold are discussed. In the case of crystalline silicon, strong variations are seen in the L2,3 emission for excitation energies up to 30 eV above threshold. These variations are shown to be dependent on the crystalline order of the material and can be interpreted in terms of restrictions on the crystal momentum that arise in an inelastic scattering description of the combined absorption and emission. On the other hand this description is less relevant to the excitation-energy dependence of ionic insulators, in which strong phonon coupling removes these restrictions on crystal momentum. In the insulators B2O3 and BN strong variations in the emission are observed at threshold, upon creation of a core exciton: the exciton affects the emission through its influence on the phonon coupling as well as on the initial and final-state screening.

scholarly journals Resonant soft x-ray fluorescence studies of novel materials

10.2172/81067 ◽  
1995 ◽  
Author(s):  
J.A. Carlisle ◽  
L.J. Terminello ◽  
E.A. Hudson ◽  
E.L. Shirley ◽  
J.J. Jia ◽  
...  
Keyword(s):  
X Ray ◽  
Fluorescence Studies ◽  
Novel Materials

X-ray photoelectron core-level studies of the heavy rare-earth metals and their oxides

1977 ◽  
Vol 354 (1678) ◽  
pp. 269-290 ◽  
Keyword(s):  
Rare Earth ◽  
Rare Earth Metals ◽  
Binding Energies ◽  
Spin Orbit ◽  
Orbit Splitting ◽  
Core Electron ◽  
Multiplet Splitting ◽  
X Ray ◽  
The Core ◽  
Cast Doubt

Systematic measurements of the core-electron binding energies of the rare-earth metals terbium to lutetium, and their surface and bulk oxides, have been made with a VG-ESCA3 X-ray photoelectron spectrometer coupled with a PDP/8E computer. Comparison of the measured binding energies for the core levels with accepted tabulations reveals discrepancies that cast doubt on normally accepted values for the heavier elements. Multiplet splitting of the 4f, 4d, 4p, 4s and 5s levels is observed for the metals terbium to thulium, which have open 4f-shells. The 4f and 4d spectra of pure ytterbium and lutetium metals, with closed 4f-shells, exhibit spin-orbit doublets; whereas multiplet splitting is also detected for oxidized ytterbium, while for oxidized lutetium the simple 4f and 4d doublets are retained. Satellite structure is observed in the 4p spectra; while the 3d spectra of dysprosium and terbium - accessible to excitation by AlKα radiation - have complex structures. Spin-orbit splitting is also observed in 5p spectra for the whole of the series terbium to lutetium. The present results agree well with available high-resolution x.p.s. data, and are also in good agreement with many-electron predictions. The existence of additional structure predicted by the correlated hole theory is confirmed, and occurs at ca . 26 eV to the high binding-energy side of the most intense peak in the 4d-spectra for terbium to thulium (with incomplete 4f-shells). Measurements are also reported for bulk oxide samples, and the oxygen Is binding energies are compared for the surface oxidized metal and bulk oxides.

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