Publications [#245093] of Harold U. Baranger

Papers Published

1. Hentschel, M; Ullmo, D; Baranger, HU, Fermi edge singularities in the mesoscopic regime: Photoabsorption spectra, Physical Review B Condensed Matter and Materials Physics, vol. 76 no. 24 (December, 2007), pp. 245419, American Physical Society (APS), ISSN 1098-0121 [pdf], [doi]
   (last updated on 2026/01/15)

   Abstract:
   We study Fermi edge singularities in photoabsorption spectra of generic mesoscopic systems such as quantum dots or nanoparticles. We predict deviations from macroscopic-metallic behavior and propose experimental setups for the observation of these effects. The theory is based on the model of a localized, or rank one, perturbation caused by the (core) hole left behind after the photoexcitation of an electron into the conduction band. The photoabsorption spectra result from the competition between two many-body responses, Anderson's orthogonality catastrophe and the Mahan-Nozières-DeDominicis contribution. Both mechanisms depend on the system size through the number of particles and, more importantly, fluctuations produced by the coherence characteristic of mesoscopic samples. The latter lead to a modification of the dipole matrix element and trigger one of our key results: a rounded K -edge typically found in metals will turn into a (slightly) peaked edge on average in the mesoscopic regime. We consider in detail the effect of the "bound state" produced by the core hole. © 2007 The American Physical Society.