共查询到20条相似文献,搜索用时 15 毫秒
1.
N. Bergeard M. G. Silly D. Krizmancic C. Chauvet M. Guzzo J. P. Ricaud M. Izquierdo L. Stebel P. Pittana R. Sergo G. Cautero G. Dufour F. Rochet F. Sirotti 《Journal of synchrotron radiation》2011,18(2):245-250
Synchrotron radiation time structure is becoming a common tool for studying dynamic properties of materials. The main limitation is often the wide time domain the user would like to access with pump–probe experiments. In order to perform photoelectron spectroscopy experiments over time scales from milliseconds to picoseconds it is mandatory to measure the time at which each measured photoelectron was created. For this reason the usual CCD camera‐based two‐dimensional detection of electron energy analyzers has been replaced by a new delay‐line detector adapted to the time structure of the SOLEIL synchrotron radiation source. The new two‐dimensional delay‐line detector has a time resolution of 5 ns and was installed on a Scienta SES 2002 electron energy analyzer. The first application has been to characterize the time of flight of the photoemitted electrons as a function of their kinetic energy and the selected pass energy. By repeating the experiment as a function of the available pass energy and of the kinetic energy, a complete characterization of the analyzer behaviour in the time domain has been obtained. Even for kinetic energies as low as 10 eV at 2 eV pass energy, the time spread of the detected electrons is lower than 140 ns. These results and the time structure of the SOLEIL filling modes assure the possibility of performing pump–probe photoelectron spectroscopy experiments with the time resolution given by the SOLEIL pulse width, the best performance of the beamline and of the experimental station. 相似文献
2.
Resonant inelastic X-ray scattering (RIXS) at the transition-metal K-edge is studied as a tool to detect the electronic structure in correlated electron systems. We, in particular, focus on the polarization dependence of RIXS intensity and symmetry of the electronic excitations. It is shown that by analyzing the polarization of the initial and scattered X-rays, the symmetry of the 4p orbitals are selected. Combined effects of the polarization of X-rays and the momentum transfer in the scattering are also studied. 相似文献
3.
This paper describes design considerations, input lens analysis, ray-tracing studies, construction details and initial tests of a Kuyatt—Simpson-type photoelectron energy analyzer. The analyzer has been designed specifically for angle-resolved photoemission studies using synchrotron radiation. Design features include input and output lens systems which establish virtual slits and apertures which define the input solid angle and source region. Constant angular resolution, constant energy-resolution and constant transmission are achieved by the analyzer. The performance of the analyzer has been checked analytically using computer ray-tracing techniques and experimentally. Initial tests have verified the ray-tracing results and have shown that all the analyzer design specifications have been realized. 相似文献
4.
V. A. Belyakov 《JETP Letters》1998,67(1):8-14
A theoretical analysis is presented of the possibilities of satisfying the conditions of phase matching (PM) in the coherent inelastic Mössbauer scattering (CIMS, which is scattering accompanied by the creation or annihilation of phonons) of synchrotron radiation (SR) and the conditions under which the maximum intensity of CIMS obtains are studied. Of the two types of CIMS — 1) participation of phonons in a scattering event only in the stage of absorption or only during re-emission of a photon, and 2) participation of phonons in both stages of scattering — PM is possible only in the first. The process in which phonons participate only at the photon absorption stage leads to efficient conversion of the SR from a wide spectral line into a narrow line, determined by the width of the Mössbauer transition. Photons of this type of CIMS effectively possess a higher penetrating power than the standard Mössbauer radiation, and their spectral distribution is shifted somewhat in the direction of low frequencies. 相似文献
5.
Doping with transition metal ions in TiO2 has been found effective to modify the electronic structure of TiO2 nanoparticles. Application of synchrotron radiation photoelectron spectroscopy (SRPES) to Nd-doped TiO2 nanoparticles revealed that there existed different peak positions and structure with different doping concentration in the valence band spectra. From the onset of valence band spectrum, it was observed that doping Nd ions alters the electronic structure and makes the band gap of TiO2 narrow. 相似文献
6.
A one-dimensional quantum model for nuclear resonant scattering using synchrotron radiation has been developed. This model
gives a clear physical interpretation of the most prominent features of the coherent forward scattering process namely, the
“speed-up” and “dynamical beat” effects. The form of the solution, for the time-dependent forward scattered intensity of the
resonant radiation from the resonant medium after synchrotron radiation excitation, is a finite series. This unique solution
can be interpreted in terms of a summation over all multiple forward scattering paths the radiation takes in reaching the
detector. The resonant medium is represented by a linear chain of N effective resonant nuclei. The analysis starts from a coupled set of quantum mechanical equations for the relevant amplitudes
in frequency space. Transformation to the time domain gives an analytical expression for the forward scattered intensity.
The contribution of every order of the multiple scattering processes from the N effective nuclei appears naturally. The expression gives a clear physical understanding of all relevant aspects of resonant
forward nuclear scattering. Furthermore, the present formalism allows the consideration of incoherent processes. This permits
the study of processes in which there is gamma emission with recoil or emission of internal-conversion electrons.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
7.
The removal of the native oxides from the In0.53Ga0.47As surface by exposure to atomic hydrogen has been investigated by highly surface sensitive synchrotron radiation based photoelectron spectroscopy. This shows that it is possible to fully remove the arsenic oxides at low temperatures, while still leaving a low concentration of stable Ga2O and In2O at the surface, and no evidence of indium loss from the substrate. The removal of surface carbon contamination is also seen, however full removal is only detected in the absence of prior substrate annealing. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
8.
The observation of adsorbate vibrational energies in the range, 30 ?, hvvib ? 1000 meV, by electron-energy-loss spectroscopy, provides detailed information on the geometry of atomic and molecular complexes. The “surface normal dipole selection rule”, is discussed and illustrated with results obtained for CO and C2H2 adsorption on the principal low-index faces of tungsten, viz.: W(100), W(110) and W(111) using a high-resolution electron reflection spectrometer. Specifically, the behaviour of chemisorbedd diatomic carbon monoxide and polyatomic acetylene is compared as a function of coverage and surface crystallography. Comparison is made with the spectral information obtained by reflection infrared spectroscopy and recent ultraviolet photoelectron spectroscopy studies of the chemisorption binding energies. The energy loss spectra are discussed in terms of current adsorbate models and the possible formation of “distorted rehybridized surface molecular complexes” based on molecular orbital theories of organometallic compounds. 相似文献
9.
G. Barone L. H. Böttger J. A. Wolny H. Paulsen A. X. Trautwein A. Silvestri I. Sergueev G. LaManna 《Hyperfine Interactions》2005,165(1-4):299-302
Nuclear inelastic scattering (NIS) of synchrotron radiation has been used to investigate the dynamics of tin ions chelated
by DNA. Theoretical NIS spectra have been simulated with the help of density functional theory (DFT) calculations using 12
models for different binding sites of the tin ion in (CH3)Sn(DNAPhosphate)2. The simulated spectra are compared with the measured spectrum of the tin–DNA complex. 相似文献
10.
The relative electron inelastic scattering mean-free-path in gold in the energy range 60–140 eV has been determined by the overlayer technique using synchrotron radiation photoemission spectroscopy from the 4f core levels of a tantalum foil substrate. The mean-free-path falls rapidly from 60 to 80 eV but is essentially constant from 100 to 140 eV. 相似文献
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13.
异质结结构界面的能带带阶是一个非常重要的参数,该参数的精确确定直接影响异质结的光电性质研究以及异质结在光电器件上的应用.利用同步辐射光电子能谱技术测量了ZnO/PbTe异质结结构的能带带阶.测量得到该异质结价带带阶为2.56 eV,导带带阶为0.49 eV,是一个典型的类型I的能带排列.利用变厚度扫描的测量方法发现,ZnO/PbTe界面存在两种键,分别是Pb—O键(低结合能)和Pb—Te键(高结合能).在ZnO/PbTe异质结界面的能带排列中导带带阶较小,而价带带阶较大,这一能带结构有利于PbTe中的激发电子输运到ZnO导电层中.该类结构在新型太阳电池、中红外探测器、激光器等器件中具有潜在的应用价值. 相似文献
14.
15.
Claudia Draxl 《Few-Body Systems》1987,2(3):N49-N49
16.
Thomas Schramm Gerd Ganteför Andras Bodi Partick Hemberger Thomas Gerber Bernd von Issendorff 《Applied Physics A: Materials Science & Processing》2014,115(3):771-779
A new experimental setup for photoelectron spectroscopy of size-selected cluster ions using synchrotron VUV radiation as generated by the Swiss Light Source is presented. An intense positively charged cluster ion beam is produced in a high-intensity magnetron sputter source. The clusters are subsequently mass selected in a sector magnet. To maximize the residence time of the cluster ions in the ionization region of the velocity map imaging spectrometer, the cluster ion beam is decelerated where it crosses the light beam. First experiments on (MoO3) n + (n = 69 and 59) cluster cations show that the approach is capable of delivering photoelectron spectra of size-selected transition metal cluster ions. 相似文献
17.
The surface electronic state on the stepped surface of Cu(755) has been investigated by means of angle-resolved ultraviolet photoelectron spectroscopy using synchrotron radiation(SR-ARUPS). We have observed a free-electron-like surface state below the Fermi level. In spite of the anisotropy of the atomic arrangement due to steps, the surface state is shown to be isotropic since the dispersion profile and the peak shape are almost identical in the directions parallel and perpendicular to the steps. This result makes a clear contrast with the previous SR-ARUPS results on Ni(755) surfaces which have the surface structure similar to Cu(755). Those experimental evidences are discussed based upon the electron configurations of both metal substrates. 相似文献
18.
《Journal of Electron Spectroscopy and Related Phenomena》1986,41(2):225-233
Photoelectron asymmetry parameters (β) and partial photoionization cross-sections have been measured for ionization from the molecular orbitals of CH3F and CH3Cl using synchrotron radiation in the photon energy range 19 to 115 eV. Cooper minima are observed in the β spectra of CH3C1 for ionization from orbitals with Cl 3p character. Several shake-up bands observed in the F 2s and Cl 38 ionization energy region indicate a breakdown of the one-electron picture of ionization. The position and relative intensities of the satellite bands are compared with the results of Green's function calculations. 相似文献
19.
The azimuthal dependence of electron energy loss spectroscopy (EELS) dipole and impact scattering intensity has been measured. Spectra for a saturation coverage of H adsorbed on W(110) exhibit loss peaks due to impact scattering from adsorbate vibrational modes. The intensity of the 160 meV loss peak has been measured as a function of the azimuthal angle between the scattering plane and a mirror plane of the urface. The angular pattern has strong maxima oriented perpendicular to the <111 > rows of atoms on the surface, and has the C2v symmetry of the W(110) surface. This azimuthal dependence is strikingly different from the nearly isotropic angular dependence of dipole scattering from Cl adsorbed on W(110). Selection rules for impact scattering account for the general features of the angular pattern based on asymmetric stretch modes associated with bridge site H atoms.We have shown that the azimuthal dependence of the 36 meV Cl/W(110) dipole scattering loss peak is isotropic and that the 160 meV H/W(110) impact scattering loss peak exhibits a striking azimuthal pattern with C2v symmetry. The symmetry and deep minima suggest that selection rules play a central role in determining the azimuthal pattern. Application of these rules to two orthogonal directions (as in ref. 6) may be misleading, as is clear from Fig. 2, because essential features of the pattern will not be observed. Our analysis of the full pattern has suggested two bridge sites may be occupied at saturation coverage, but has still not resolved certain questions about the H/W(110) system.
SITE | LONG BRIDGE | SHORT BRIDGE | DISTORTED BRIDGE | |||
MIRROR PLANES | [001], [10] | NONE | [10] | |||
2-FOLD ABOUT Z | YES | YES | NO | |||
PARALLEL MODES | [001] | [10] | [11] | [12] | [001] | [10] |
DIRECTIONS OF ZERO SCATTERING | [001] * [10] | [001] * [10] | [11] [12] | [11] [12] | [001] * [10] | NA |