Springer LINK: The European Physical Journal B - Abstract Volume 5 Issue 1 (1998) pp 53-60

The European Physical Journal B

ISSN: 1434-6028 (printed version)
ISSN: 1434-6036 (electronic version)

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Abstract Volume 5 Issue 1 (1998) pp 53-60

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

K. Höppner, A. Kaprolat, W. Schülke (a)

Institute of Physics, University of Dortmund, 44221 Dortmund, Germany

Received: 29 December 1998 / Accepted: 16 March 1998

Abstract: The dynamic structure factor $S({\bf q},\o )$ 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 $S({\bf q}\o)$-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-$S({\bf q},\o )$ [#!ref12!#], 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).

PACS. 71.45.Gm Exchange, correlation, dielectric and magnetic functions, plasmons - 78.70.Ck X-ray scattering - 71.20.Dg Alkali and alkaline earth metals

(a) email: schuelke@physik.uni.dortmund.de

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