To study electron momentum densities in solids by grazing angle reflection kinematics has been shown to be feasible [S. lacobucci, S. Rioual, A. Ruocco, M. Mastropietro, G. Stefani, Surf. Sci. 454 (2000) 1026], but development of this spectroscopy has been hampered by long acquisition time; to fully exploit potentialities of this method is mandatory to reduce duration of the experiment within times comparable with clean surface lifetimes in ultra-high vacuum. This paper reports on recent developments of the reflection (e,2e) spectrometer that make a sizeable step forward in attaining this goal. It operates in asymmetric kinematics and at small grazing angle, thus allowing to enhance the surface sensitivity. A drastic reduction in acquisition time has been achieved by implementing parallel acquisition, both in energy and angle, of the detected electron pairs. To achieve parallel acquisition in energy and momentum, each of the two electron analysers is equipped with a two-dimensional position sensitive detector. A custom-made electronic hardware and software have been developed for the automatic control of the experiment and for acquisition and storage of the coincidence events. After discussing in some details the relevant features of the new spectrometer, few examples of valence band mapping and electron momentum densities measured in highly oriented pyrolitic graphite with energy and momentum resolutions of 1.3 eV and 0.15 angstrom(-1) are given. 0 2006 Elsevier B.V. All rights reserved.
Liscio, A., Ruocco, A., Stefani, G., Iacobucci, S. (2007). A high efficiency spectrometer for reflection (e,2e) experiments at surfaces RID G-7348-2011. JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA, 161(1-3), 140-146 [10.1016/j.elspec.2006.12.029].
A high efficiency spectrometer for reflection (e,2e) experiments at surfaces RID G-7348-2011
STEFANI, Giovanni;
2007-01-01
Abstract
To study electron momentum densities in solids by grazing angle reflection kinematics has been shown to be feasible [S. lacobucci, S. Rioual, A. Ruocco, M. Mastropietro, G. Stefani, Surf. Sci. 454 (2000) 1026], but development of this spectroscopy has been hampered by long acquisition time; to fully exploit potentialities of this method is mandatory to reduce duration of the experiment within times comparable with clean surface lifetimes in ultra-high vacuum. This paper reports on recent developments of the reflection (e,2e) spectrometer that make a sizeable step forward in attaining this goal. It operates in asymmetric kinematics and at small grazing angle, thus allowing to enhance the surface sensitivity. A drastic reduction in acquisition time has been achieved by implementing parallel acquisition, both in energy and angle, of the detected electron pairs. To achieve parallel acquisition in energy and momentum, each of the two electron analysers is equipped with a two-dimensional position sensitive detector. A custom-made electronic hardware and software have been developed for the automatic control of the experiment and for acquisition and storage of the coincidence events. After discussing in some details the relevant features of the new spectrometer, few examples of valence band mapping and electron momentum densities measured in highly oriented pyrolitic graphite with energy and momentum resolutions of 1.3 eV and 0.15 angstrom(-1) are given. 0 2006 Elsevier B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
