Singularities in core-level spectra near metallic surfaces

Abstract

Calculations of the screening shift and dynamical singularity index of the structureless core hole placed near and inside the metallic slab are presented, where the screening mechanism is described using the quantummechanical response function calculated in the local density approximation. Core-hole screening shifts show oscillations which are compared with the experimental results. Spatial dependence of the static singularity index, besides experimentally observed enhancement at the surface, shows some new features ͑bulk oscilla-tions͒ which were not yet experimentally observed. The dynamical singularity index is used to calculate complete core hole spectrum, including singular line shapes and bulk and surface plasmon losses, and the results explain very well some observed features in the experimental photoemission spectra.

Theory of core-level spectra in x-ray photoemission of pristine and doped graphene

“…On the other, if the substrate is metallic, the hole in the graphene monolayer can interact with the electrons in the substrate, and also show singular lineshapes, as was shown by the authors of Ref. 13. All these factors should be taken into account when trying to determine whether the observed asymmetry is due to the singular excitation of electron-hole pairs, or to low-order scattering processes.…”

“…However, this is not possible for the frequency-dependent α(ω), so we shall instead use a more general approach. 8,13 We first notice that the core-hole Green's function (12) satisfies the equation…”

“…In the following we shall make use of the formalism developed bythe authors of Ref. 13 localized levels in the vicinity of metallic surfaces, following earlier work on bulk metals. [1][2][3][4][5][6][7][8][9][10] For the localized hole only the lowest-order cumulant, shown in Fig.…”

TDDFT study of time-dependent and static screening in graphene

“…This expression resembles the dynamical singularity index used to calculate the core hole spectral function. 40 However, an important difference is that α is calculated from the induced potential obtained at different points, z = 0 and z = L 2 . For this reason we shall refer to α as a nonlocal singularity index.…”

Microscopic theory to quantify the competing kinetic processes in photoexcited surface-coupled quantum dots

“…With a few notable exceptions 4,17,18 , studies in molecular transport generally treat the electrodes as passive Fermionic reservoirs, thus ignoring the scattering of electrons in the leads as a result of the excitation dependent Coulomb potential of the molecule. Under certain conditions, discussed in this paper, this potential can significantly alter the transport and relaxation in tunneling junctions [19][20][21][22] , as well as the optical absorption 23 . For example, tunneling of an electron out of the quantum dot yields sudden transition of its charge, and can cause significant dynamical fluctuations in the surface charge density in the electrode.…”