Calculated oxygen 1s core-level photoemission spectra from cuprate superconductors

The observed O 1s X-ray photoemission spectra of the cuprate superconductors often exhibit a satellite at a higher binding energy to the main peak. The origin of this satellite is not fully understood. We have done model cluster calculations to investigate the origin of this satellite using the configuration interaction approach. The calculated spectra for the divalent and superconducting cuprates essentially exhibit a single peak. On distorting the cluster in-plane, the peak shifts to higher binding energies. This substantiates a deterioration of the surface leading to the observed satellite structure in the O 1s core-level photoemission spectra of the cuprate superconductors.     

Strong changes in the phonon spectra of 123 superconductors by varying oxygen concentration

By means of inelastic neutron scattering we have studied the phonon densities of states (PDOS) ofY based 123 superconductors with oxygen concentrations varying between O₇ and O₆. We find drastic changes in the PDOS above 40 meV which develop in a systematic manner if we switch from superconducting to semiconducting samples. Model calculations clearly show that this cannot be explained solely by structural changes but is likely to reflect strong differences in the electron-phonon coupling.     

Energy-gain satellite structure in the C(1s) x-ray photoemission spectra of organic macromolecules

Satellite peaks on the high kinetic energy side of the C(1s) photoemission line of several aromatic organic macromolecules are observed. Subsidary experiments indicate that these peaks correspond to the absorption of quanta of energy from the exciton population created at the surfaces of thin film samples by the inelastic scattering of photoelectrons not collected under the C(1s) peak. This phenomenon would then be an approximate electronic analogue to photon-vibron hot bands in the Frank-Condon effect in the optical spectroscopy of molecules.     

Unconventional phonon spectra and obstructed edge phonon modes

Based on the elementary band representations(EBR), many topologically trivial materials are classified as unconventional ones(obstructed atomic limit), where the EBR decomposition for a set of electronic states is not consistent with atomic valenceelectron band representations. In the work, we identify that the unconventional nature can also exist in phonon spectra, where the EBR decomposition for a set of well-separated phonon modes is not consistent with atomic vibration band representations(A...     

Plasmon satellites in X-ray photoemission spectra

Controversy exists whether plasmon-satellite structure observed in core-level photoemission spectra arises from so-called intrinsic or extrinsic plasmo     

Strong oscillations in molecular valence photoemission intensities

Photoemission from the two outermost ionizations [highest occupied molecular orbitals (HOMO and HOMO-1)] of Mg(eta(5)-C(5)H(5))(2) has been studied with synchrotron radiation in the gas phase. Strong oscillations in the HOMO-1/HOMO ratio, qualitatively similar to those well-known for fullerenes, are found. Excellent agreement with the experimental ratio is provided by accurate cross section calculations both at the density-functional theory and time-dependent density-functional theory level, indicating that a many electron response has a minor role for this effect. A comparison with the calculated values for other metal sandwich compounds indicate that the presence of oscillations is a widespread phenomenon, and a potential source of interesting information on the structural and electronic properties of the target molecule.     

Theory of satellites in photoemission and inverse photoemission spectra of 4 f materials

We present calculations of the relative intensities and peak separations of the f derived spectral density for the, integer valent, light rare earths. We consider both f derived photoemission and inverse photoemission spectra. In these types of experiments, the final states has either an excess or a deficiency of charge residing on the screened by the conduction electrons. If the screening interaction is This may give rise to the appearance of satellites in both photoemission and inverse photoemission spectra. However, the calculations indicate that the relative intensity of the f derived satellite in the inverse photoemission spectrum should be extremely weak, when compared to the intensity of the satellites in the photoemission experiment.     

Franck-condon-broadened angle-resolved photoemission spectra predicted in LaMnO3

The sudden photohole of least energy created in the photoemission process is a vibrationally excited state of a small polaron. Therefore the photoemission spectrum in LaMnO3 is predicted to have multiple Franck-Condon vibrational sidebands. This generates an intrinsic line broadening approximately 0.5 eV. The photoemission spectral function has two peaks whose central energies disperse with bandwidth approximately 1.2 eV. Signatures of these phenomena are predicted to appear in angle-resolved photoemission spectra.     

Effects of short-range magnetic order on photoemission and inverse photoemission spectra in iron

The dependenc of spin-resolved photoemission and inverse photoemission spectra on short-range magnetic order below and aboveT _c is investigated within a bulk interband transition model. The spectra are calculated in a 2000-atom cluster of bcc-Fe with local exchange field configurations, which are random subject to an assumed spin-correlation function. The model continuously bridges the gap between the disordered-local-moment picture (no short-range order) and a local-band picture (massive short-range order). Special emphasis is given to the analysis of factors like group velocity and the symmetry of the wave function by investigating special points in the Brillouin zone. Comparison with experimental data reveals a short-range order of at least 4 Å (corresponding to a nearest-neighbour correlation of about 0.4) nearT _c .     

Theoretical study of phonon spectra in ferromagnetic nanoparticles

Based on the spin-phonon model we analyze the influence of surface and size effects on the phonon properties of ferromagnetic nanoparticles. A Green's function technique in real space enables us to calculate the renormalized phonon energy and its damping depending on the temperature and the anharmonic spin-phonon interaction constants. With decreasing particle size the phonon energy can decrease or increase for different surface spin-phonon interaction constants, whereas the damping increases always. The influence of an external magnetic field is discussed, too. The theoretical results are in reasonable accordance to experimental data.     

Cooper minima in the photoemission spectra of solids

Variations of the photoionization cross section of valence states as a function of interatomic distance are studied by means of atomic and solid-state density functional approaches and compared with photoemission data. In contrast to the free atom case, a series of Cooper minima is found for 4d, 5d, and 5f states in Pd, Ag, Au, and U metals. The discovered fundamental phenomenon is of high importance for the correct interpretation of photoemission data.