Resonant Inelastic X-Ray Scattering at the K Edge of Ge

We study the resonant inelastic x-ray scattering (RIXS) at the $K$ edge of Ge. We measure RIXS spectra with systematically varying momenta in the final state. The spectra are a measure of exciting an electron-hole pair. We find a single peak structure (except the elastic peak) as a function of photon energy, which is nearly independent of final-state momenta. We analyze the experimental data by means of the band structure calculation. The calculation reproduces well the experimental shape, clarifying the implication of the spectral shape.Comment: 17 pages,9 figures, Please also see our related paper: cond-mat/040500

Nichtdiagonale Response in Silizium Inelastische Roentgenstreuexperimente aus stehenden Wellenfeldern mit Synchrotronstrahlung und deren Interpretation

SIGLEAvailable from TIB Hannover: DW 5730 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Resonant fluorescence emission from the Ge and Cu valence band

Working out the calculation of the double differ-ential scattering cross section for resonantly excited X-rayemission from valence bands, one ends up [7] with a law ofmomentum conservation, combining Bloch-k-vectors of theenvolved electrons and the incoming and outgoing photon.This leads to a rich structure of the fluorescence line that re-veals properties of the underlying electronic band structure.First experiments in the hard X-ray region onGeandCuare presented, showing, that momentum conservation in theresonant absorption-emission process hold

Nondiagonal response of Si by inelastic-x-ray-scattering experiments at Bragg position: Evidence for bulk plasmon bands

Inelastic scattering of x-ray photons from standing-wave fields is used to measure nondiagonal elements of the dielectric-response matrix of Si. A peak-valley structure for $q \lt q_c$ is found, due to the fact that bulk plasmon bands, split near the zone boundary, contribute with different signs; hence, direct evidence for the existence of plasmon bands is obtained. Such detailed studies of the response matrix, together with the proposed plasmon-band model, offer a new access to dynamical screening in an inhomogeneous electron system

Semiempirical local-field correction function for electrons in Li metal

A frequency average of the complex local-field correction function (LFCF), G(q, ¯ω), of electrons in Li metal has been semiempirically determined for 1.12kF1.6kF, the semiempirical ReG(q, ¯ω) exhibits a strong increase in values ranging from 1.2 to 2.4 in a manner which has not been predicted by any existing theory. The relation between G(q, 0) and the momentum distribution function n(k) is stressed to make contact with a most recently found anomalous behavior of n(k) in Li

Fano-like coupling of collective and particle-hole excitations in Li metal

The dynamic structure factor $S({\bf q},\omega)$ of Li with ${\bf q}\parallel$ [110] and 0.88 a.u. < q< 1.03 a.u., as measured with 1 eV resolution by means of synchrotron radiation based inelastic X-ray scattering spectroscopy (IXSS), exhibits, in the energy loss range between 3 and 12 eV, a fine structure, which appears as a resonance around 4 eV and an antiresonance around 8 eV, when the difference between the experimental $S({\bf q}\omega)$-spectra with ${\bf q}\parallel$ [110] and ${\bf q}\parallel$ [111] is considered. In order to find out the origin of this fine structure we have interpreted recent TLDA (time dependent local density approximation) calculations of the Li-$S({\bf q},\omega)$ [CITE], which were based on the inversion of the full dielectric matrix, by utilizing a simple two-plasmon-band model. In this way the fine structure can be traced back to a Fano-like coupling of the discrete collective excitations (both the regular plasmon and the so-called zone-boundary collective states (ZBCS's)) and the particle-hole excitation continuum, mediated by the off-diagonal elements of the dielectric matrix, $\varepsilon_{\bf 0G}$, where ${\bf G}=(2\pi /a)$ (1,1,0)

Effect of thermal vibration and the solid-liquid phase transition on electron dynamics: An inelastic x-ray-scattering study on Al

Inelastic-x-ray-scattering measurements of the dynamic structure factor, S(q,ω), of electrons in Al both in the solid phase at rising temperatures and in the liquid are presented. The double-peak structure of S(q,ω) for q>qc (qc=plasmon cutoff vector), diminishes gradually with decreasing strength of the ion-core potential; the peak position and the sloping plateau of the S(q,ω) spectra for q>qc do not exhibit marked changes upon melting. The plasmon energy for q<qc shifts according to the variation of the electron density upon heating and melting, and does not respond to the loss of long-range order

Electron momentum-space densities of Li metal: A high-resolution Compton-scattering study

Directional Compton profiles (CP’s) of Li metal were measured for 11 directions of the momentum transfer q with 0.14 a.u. (a.u.=atomic units: ħ=e=m=1) momentum-space resolution using synchrotron radiation from the DORIS (Doppel-Ring-Speicheranlage) storage ring monochromatized to 31 keV. Both the total valence-electron CP’s and the directional differences of the CP’s exhibit considerable deviations from the most recent density-functional calculations, performed by Sakurai et al. [Phys. Rev. Lett. 74, 2252 (1995)] within the limits of the local density approximation. These discrepancies are attributed to self-energy effects connected with the excitation of so-called plasmaron modes. The three-dimensional (3D) valence-electron momentum density, ρ(p), as well as the 3D occupation number density N(k), were reconstructed using the Fourier-Bessel method. The reconstructed ρ(p) exhibits clear evidence of higher momentum components due to 110 umklapp processes. The reconstructed N(k) enables a direct experimental access to the Fermi-surface anisotropy of Li, which was found to be 3.6±1.1%. The reconstructed N(k) for k∥ [001] was fitted to a model with the renormalization factor z as the only free parameter, which was found to be z=0.1±0.1