Historical sketch
just a few words about our background
25 March 1999
In the early eighties some people from
the University of Camerino participated to the first x-ray
absorption measurements collected at the national synchrotron
radiation (SR) facility (ADONE @
Laboratori Nazionali di Frascati) in
the framework of the PULS (Progetto per l'Utilizzazione della
Luce di Sincrotrone) project. These scientists were A. Bianconi,
S. Stizza and I. Davoli. Some more information about the development of
Physics at Camerino can be found
here.
In the late eighties Prof. S. Stizza obtained funding and
attracted collaborators in forming a research group on x-ray
absorption spectroscopy (XAS) at the Camerino University. Efforts
were concentrated on the installation of a RIGAKU laboratory
EXAFS equipment at the Centro Grandi Apparecchiature (C.I.G.A.) of the Camerino University and on the development of XAS data-analysis programs using multiple-scattering theory.
M. Berrettoni was hired as a technician for the EXAFS laboratory equipment and A. Di Cicco joined the group as a researcher.
In the early 90s the activity was concentrated on the
development of advanced "ab-initio" data-analysis methods
(GNXAS) in collaboration with C. R. Natoli
(Laboratori Nazionali di Frascati)
and A. Filipponi
(Universita` dell'Aquila) and on the performance of x-ray absorption measurements at international
synchrotron radiation facilities (LNF
and
LURE).
In the 1990-1994 period the main
research activities regarded:
1) development of computer codes (GNXAS)
able to use multiple-scattering (MS) theory for X-ray absorption
data-analysis. This has been a long-term project research
conducted mainly by Filipponi and Di Cicco and inspired by Natoli
who provided also the computer codes for phase-shift
generation.
2) Application of MS theory for x-ray
absorption data-analysis in systems of known structure. Important
initial applications were on SiX4 molecules, brominated
molecules, bromine, silicon, iron.
The aim was to study distance and bond-angle distributions in
molecules and crystals. This research was mainly conducted by Di
Cicco and Filipponi involving also several other collaborators
and research groups (S. Stizza, P. D'Angelo, V.
Pavel).
3) Design and realization of XAS
measurements on liquid and supercooled metals. Study of local
two-atom and three-atom distributions in monoatomic liquids.
This project was realized by Filipponi and Di Cicco using
dedicated SR beamtime at LURE. First experiments regarded liquid
and undercooled Ga and Hg dispersed in epoxy resin.
Preliminary XAS measurements were obtained using the laboratory
XAS equipment at Camerino. Other low-melting point metals (Sn,
In, Pb, Bi) were investigated at LNF and LURE using conventional
furnaces. Samples were realized at the University of Camerino
using our Leybold metal evaporator.
4) Absorption and photoemission study of
many-electron channels in core-level spectra.
The opening of two-electron channels in the atomic background of
the x-ray absorption spectra was studied in silicon-based
molecules, bromine and in sixth-period molten metals (Di Cicco,
Filipponi and D' Angelo).
The Mg KL (1s2p) shake-up satellites in solid MgO and MgF2 were
studied at Camerino University using a MAC 2 electron
spectrometer and a conventional x-ray source (Di Cicco and De
Crescenzi).
5) XAS studies of High-Tc
superconductors and related compounds.
The local structure around Cu in YBaCuO, BSSCO and some related
compounds was accurately investigated focussing the attention on
the in-plane oxygen distortions (Di Cicco, Berrettoni,
Stizza).
Created on 25 Mar 1999 - Responsible: A. Di Cicco
Local date/timeast:
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