Analisi fine della materia disordinata

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Analisi fine della materia disordinata

• Personale CNR
• Marco Zoppi primo ricercatore
• Ubaldo Bafile ricercatore
• Lorenzo Ulivi ricercatore
• Milva Celli ricercatore
• Daniele Colognesi ricercatore
• Collaboratori
• Francesco Grazzi Assegno di ricerca
• Alessandra Giannasi Dott. Ricerca
• Giacomo Corradi Borsa di studio CNR

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Descrizione del gruppo

• Base culturale comune Fisica dei Liquidi
• Struttura microscopica - potenziali
  intermolecolari
• Dinamica microscopica - proprietà di trasporto
• Caratterizzazione sperimentale
• Spettroscopia ottica
• Scattering Raman (livelli inter- e
  intra-molecolari)
• Scattering di Brillouin (modi idrodinamici)
• Spettroscopia e diffrazione, neutronica e X
• Simulazione (MC, MD, PIMC)
• Fisica delle Alte e Altissime Pressioni
• Impegni (tempi brevi)
• strumentazione avanzata per neutroni
• immagazzinamento di Idrogeno

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microscopic structure and dynamics of fluids
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microscopic structure (and dynamics) of fluids
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microscopic (structure and) dynamics of fluids
neutron scattering
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a neutron scattering experiment
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neutron diffraction (k0 k1)
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Problem the structure liquid Hydrogen

• the most abundant element in the universe
• the simplest atomic system
• the simplest molecule
• no structural information until 1989 why ?
• molecular hydrogen carries 2 electrons only
• practically invisible to X-rays
• neutrons?

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hydrogen and the neutrons

• neutron cross section

proton coherent cross section
proton incoherent cross section
much better situation for deuterium
deuton coherent cross section
deuton incoherent cross section
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quantum Boltzmann liquids structure of deuterium
Exp. SANDALS _at_ ISIS
M. Zoppi, U. Bafile, et al. P.R.B 48, 1000
(1993) P.R.L. 75, 1779 (1995) P.R.E 54, 2773
(1996)
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liquid hydrogen structure
M. Zoppi, M. Celli, A.K. Soper, Phys. Rev. B 58,
11905 (1998) M. Celli, N. Rhodes, A.K. Soper, M.
Zoppi, J. Phys. Cond. Matt. 11, 10229 (1999) M.
Zoppi, U. Bafile, M. Celli, ... et al. J. Phys.
Cond. Matt. 15, S107 (2003) M. Celli, U. Bafile,
...., M. Zoppi, Submitted to PRB, Oct. 2004.

• meanwhile, from X-ray experiments (ESRF)
• G. Pratesi, D. Colognesi...et al. Philos. Mag. B
  82, 305 (2002)
• ... G. Pratesi, D. Colognesi...et al. J. Low
  Temp. Phys. 129 117 (2002)

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microscopic (structure and) dynamics of fluids
collective motions
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Collective dynamics of fluids
in the case of neutrons
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memory function approach

• Small Q and ?
• the fluid has time to relax towards
  equilibrium, with viscous dissipation
• Large Q and ?
• the fluid behaves as an elastic (disordered)
  solid

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Neutron Brillouin Scattering
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X-ray Brillouin scattering
At slightly larger Q or E, X rays too come into
play, thanks to recent advances in
high-resolution inelastic scattering
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Fast sound in binary mixtures He0.65 - Ne0.35
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microscopic (structure and) dynamics of fluids
self motions
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Main incoherent INS regimes
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INS velocity auto-correlations in H2 and H2D2
D. Colognesi, M.Celli, M. Neumann and M. Zoppi,
Phys. Rev. E (2004) in press
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Extension to solid systems from LiH to CsH
J. Boronat, C. Cazorla, D. Colognesi, and M.
Zoppi, Phys. Rev. B 69, 174302 (2004).
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microscopic (structure and) dynamics of fluids
high pressure science
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High pressure science

• Fundamental physics (hydrogen metallization)
• Molecular crystals (phase diagrams)
• Polymerization ? Metallization
• Mixtures (stoichiometric compounds)
• Earth Physics (internal core, rocks melting ...)
• Planetary atmospheres (Jupiter, Saturn, ... )
• Material science (ultra hard complex materials)

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Diamond Anvil Cell
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High pressure Hydrogen

• Free rotor approximation holds up to high
  pressure hcp(J is a good quantum number).
• Increasing pressure
• Freezing of rotational dynamics
• Orientational transitions observed at 120-150
  GPa(1.2-1.5 Mbar) in para-H2

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Internuclear distance of hydrogen
Solid hcp

• collective rotational excitations
• 3rd order perturbation theory

Rotational Raman Scattering in fluid and solid H2
at room temperature. P 0 - 20 GPa (0 - 200
kbar) gray dots L. Ulivi, M. Zoppi, L. Gioè,
G. Pratesi, Phys. Rev. B58, 2383, (1998)
F. Grazzi, M. Moraldi, L. Ulivi, Europhys. Lett.
in press
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stoichiometric compoundsAr(H2)2, Ne (He)2,
CH4 (H2)2, He(N2)11 , ...

• Almost free rotation of hydrogen molecule

L. Ulivi, R. Bini, P. Loubeyre, R. LeToullec, H.
Jodl Phys. Rev. B 60 6502 (1999) F. Grazzi L.
Ulivi, Europhys. Lett., 52, 564 (2000).
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Rotons in Ar(H2)2 anisotropic potential
F. Grazzi, M. Santoro, M. Moraldi, L. Ulivi,. P.
R. L. 87, 125506 (2001)F. Grazzi, M. Santoro, M.
Moraldi, L. Ulivi, P. R. B 66 144303 (2002)
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Solid Oxygen x-ray diffraction (ESRF)

• Only the a phase exists at low P and T

Molecule associationSpectroscopy Magnetic
PropertiesSpectroscopyNeutron Diffraction
F. Gorelli, M. Santoro, L. Ulivi, M. Hanfland
Phys. Rev. B 65 172106 (2002)
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IR absorption in the e-phase
F. Gorelli, L. Ulivi, M. Santoro, R. Bini Phys.
Rev. Lett. 83 4093 (1999) Phys. Rev. B63 104110
(2001).
Physics Today, Dec. 1999 p.9
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Solid oxygen magnetic properties
F. Gorelli, L. Ulivi, M. Santoro, R.Bini, Phys.
Rev. B62, R3604 (2000).
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Solid oxygen high pressure neutron diffraction
ExperimentLLB, G6.1sapphire anvil
cell Different magnetic order betweena- and
d-phase
I.N. Goncharenko, O.L. Makarova, L. Ulivi, Phys.
Rev. Lett. 93, 055502 (2004)
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Prospettive a medio-lungo termine
sistemi complessi
Prospettive a breve termine

• Immagazzinamento dellIdrogeno (EU-FP6)
• materiali nanoporosi (nanotubi di carbonio)
• idruri metallici (diagnostica neutronica)
• idruri metallorganici (neutroni, luce, H.P.)
• Strumentazione neutronica avanzata
• Progetto INES (in fase di completamento)
• Progetto NIMROD (EU-FP6)

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H-storage in carbon nanotubeswhere is hydrogen?
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neutron diffraction experimentSANDALS _at_ ISIS
From the differences in the two diffraction
patterns we will obtain information on the C-D
correlation.
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CNR-CCLRC international cooperation

• 1991-1995 SERC-CNR agreement for access to ISIS
• 5 utilization level - (4) Access (1)
  Instrument PRISMA
• 1996-2001 First renewal (CCLRC-CNR)
• 5 utilization level - (4) Access (1)
  Instrument TOSCA
• 2001-2004 Italian Neutron Experimental
  Station (INES)
• 50 utilization level for CNR (in
  progress, commissioning early 2005)
• 2002-2008 Second renewal (CCLRC-CNR)
• 4 utilization level - (3) Access
  (1) Instrument NIMROD

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The TOSCA project (1996-2001)
CNR investment 3.2 GLit. 1 of ISIS
An international cooperation between CNR and
CCLRC(UK) ISIS pulsed neutron source www.ifac.cnr.
it/tosca/tosca-main.htm
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The INES project (2001-2004)

• CNR investment
• 600 keuro.
• reserved utilization
• 50 for Italians

Within the framework of the international
cooperation between CNR and CCLRC(UK) ISIS pulsed
neutron source www.ifac.cnr.it/ines/ines-main.htm
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The NIMROD project (2004-2008)
CNR investment 1560 k-euro 1 ISIS
Within the framework of the international
cooperation agreement (2002-2008) between CNR and
CCLRC for the utilization of the ISIS pulsed
neutron source
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grazie della vostra attenzione !