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 ◽  
...  

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.

2013 ◽  
Vol 27 (16) ◽  
pp. 1330012 ◽  
Author(s):  
A. KOTANI

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.


2013 ◽  
Vol 93 ◽  
pp. 82-86 ◽  
Author(s):  
Krzysztof Banas ◽  
Agnieszka M. Banas ◽  
Mariusz Gajda ◽  
Wojciech M. Kwiatek ◽  
Bohdan Pawlicki ◽  
...  

2011 ◽  
Vol 83 (4) ◽  
Author(s):  
W. Cao ◽  
M. Kavčič ◽  
J.-Cl. Dousse ◽  
M. Berset ◽  
K. Bučar ◽  
...  

1998 ◽  
Vol 96 (1-3) ◽  
pp. 187-194 ◽  
Author(s):  
E.Z. Kurmaev ◽  
V.M. Cherkashenko ◽  
M. Neumann ◽  
S. Stadler ◽  
D.L. Ederer ◽  
...  

1986 ◽  
Author(s):  
K.L. Tsang ◽  
C.H. Zhang ◽  
T.A. Callcott ◽  
E.T. Arakawa ◽  
D.L. Ederer

Author(s):  
M. A. Ramazanov ◽  
S. G. Nuriyeva ◽  
H. A. Shirinova ◽  
A. H. Karimova ◽  
M. A. Nuriyev

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.


1994 ◽  
Vol 375 ◽  
Author(s):  
J. A. Carlisle ◽  
E. L. Shirley ◽  
L. J. Terminello ◽  
E. A. Hudson ◽  
J. J. Jia ◽  
...  

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


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