Transcript Inelastic UV Scattering as a new Technique to Investigate

Science frontiers with the FERMI@elettra Free Electron Laser
C. Masciovecchio, F. Parmigiani
Elettra Synchrotron, S.S. 14 km 163,5 – 34012 Basovizza, Trieste – Italy
•
FERMI@elettra
•
DIPROI (DIffraction & PROjection Imaging) beamline
M. Kiskinova
•
LDM (Low Density Matter) beamline
C. Callegari
•
EIS (Elastic & Inelastic Scattering) beamline
C. Masciovecchio
•
Conclusions
Why Free Electron Lasers ?
Emitted photons (x1014)
8
6
4
2
Synch. × 1000
0
-30
-15
0
15
30
Time (ps)
From CW (MHz) to Pulsed (kHz) sources
Different Experiments and Physics
!
Why Free Electron Lasers ?
Time-scales of dynamic processes occurring in matter
Chemical
transformations
Intermolecular
energy transport
Electron-spin
dynamics
Domain
dynamics
Diffusion
e-ph/ph-ph
scat
Imaging with high Spatial Resolution (~ l): fixed target imaging, particle injection imaging, …..
Dynamics: four wave mixing (nanoscale), warm dense matter (uniform heating), exterme condition, ....
Resonant Experiments: XANES (tunability), XMCD (polarization), chemical mapping, ……
FERMI@elettra
LINAC
Bunch
compressor
Bunch
compressor
Injector
95 MeV
1.5 GeV
UNDULATOR05/2010
EXP HALL05/2010
Seed
laser(s)
EOS
DS
DS
Linac 
Beam
spreader
M1
Delay
M2
R1
M
DS
FEL-1 (21m)
R
FEL-2 (38 m)
~20 m
2 m
Front
ends
R2
First stage
Second stage
x 105
The pulse in time is Transform Limited
L. H. Yu et al., 91, 074801 PRL (2003)
FERMI@elettra
Tunability: (fast) 5 – 20% at a given Energy
Polarization: Circular V and H
Beam Profile: ~ Transform Limited (10 – 1000 fs)
When?
FEL1 Oct 2010 switch on
FEL2 Jul 2011 switch on
FERMI@elettra
Sep 2009
LDM
LDM
Monochromator
Shutters
Spectrometer
Plane mirrors
KB Systems
Delay Lines
FEL 1
6º
2.5°
2.5°
4º
5°
75.1/61.1
2.5°
FEL 2
I0 monitors
Safety
Hutch
EIS
Switching
DIPROI
6º
TIMEX
focusing
DIPROI (DIffraction & PROjection Imaging) beamline
LDM (Low Density Matter) beamline
EIS (Elastic & Inelastic Scattering) beamline
TIMER
TIMEX
DIPROI beamline
M. Kiskinova
H. Chapman, S. Bajt, Lars Gumprecht (DESY); A. Barty, B. Woods, M. Bogan, E. Spiller, M. Pivovaroff, A. Nelson (LLNL); U. Vogt,
H. Hertz (KTH Stockholm); G. Morrison (King’s College); D. Cojoc (TASC); F. Capotondi, D. Cocco, E. Pedersoli, M. Zangrando,
F. Parmigiani (Sincrotrone Trieste)
Stepping into nano-world
Scanning microscopes are limited to surfaces
Transmission electron microscopes are limited
in penetration (samples thinner than ~ 30 nm)
Imaging
Limitations of available techniques:
X-ray crystallography reveals the 3D atomic
structures, but requires crystals
The optic-imposed resolution limitations can be
overcome by image reconstruction from the
measured coherent X-ray diffraction pattern of
a sample
Scattering
X-ray microscopes are limited in resolution
by the optical elements, and coherence
DIPROI beamline
Specific element-sensitive
Abrupt changes in the X-ray scattering
cross section near electronic
resonances: the difference in CDIs can
be used for make a “chemical map” of a
specific element
Song et al., PRL 100, 25504, 2008
Buried Bi structures inside a Si crystal with
a pixel resolution of ~ 15 nm
DPC
Fe
Co
CoFe2O4 in mouse 3T3 fibroblast cells
“
...this imaging technique is also sensitive to chemical states via near-edge resonances and can be
extended to exploit other contrast mechanisms depending on resonant transitions such as x-ray
magnetic circular dichroism.......electronic orbital as well as chemical state specific imaging of
magnetic materials, semiconductors, organic materials, biominerals, and biological specimens...”
Fe MII 3p1/2 is at ~ 53 eV
DIPROI beamline
Gaps in our current understanding of effect of Nano-Objects (NOs) introduced
in biological systems and vice-versa (cell targeting, drug delivery, etc)
N. Lewinski et al., Small 4, 26, (2008)
Today NOs production is ~ 2000 tons  in 2020 will be ~ 60000 tons !!
UV -Photochemistry (NOB)
H2O
O2OH
O2
eh+ → e-
Oxidative damage due to catalysed generation of
reactive oxygen species, ROS, (OH, O2-, H2O2) –
impact on the NOs?
Bond breaking and release of free radicals or
molecules – impact on the NOs?
FEL
Me++
H2O2 OH-
CCD
Sample(s)
Imaging to study the alteration of cell’s
morphology due to the presence of NOs and
determine their spatial distribution
LDM beamline
C. Callegari
F. Stienkemeier, B. von Issendorff (Univ. of Freiburg); S. Stranges (University of Rome); T. Möller, C. Bostedt (TU-Berlin); U.
Buck (Göttingen); K. Fauth (Univ. of Würzburg); M. Drabbels (EPFL Lausanne); M. Schmidt (Orsay); H.N. Chapman (DESY);
P. Hammond (Perth); P. Decleva (Univ. of Trieste); J.M. Dyke (Univ. of Southampton); J.‐E. Rubensson, J. Nordgren (Univ. of
Uppsala); K. Prince, R. Richter, D. Cocco, M. Zangrando, F. Parmigiani (Sincrotrone Trieste)
Fundamental physics:
• Structure of nano clusters
• Ionization dynamics
• Superfluidity – relaxation dynamics
• Non‐linear optics
• Chirality
Material science:
• Electronic properties of organic nanostructures
• Charge transfer dynamics in heterogeneous structures
• Magnetism of nanoparticles
• Catalysis in nanomaterials
Biochemistry:
• Micro solvation of bio‐molecules
Aerosol / Atmospheric chemistry:
• Reactions at microscopic water interfaces
LDM beamline
HElium NanoDroplet Isolation (HENDI) will provide molecules, clusters and
nanostructured complexes at ultracold temperatures.
The droplets cool the embedded species to a temperature of 380 mK  only vibrational
ground states are populated
Circular dichroism in free ultra-cold nanoparticles
Magnetic particles embedded in helium droplets at low temperatures
aligned by weak magnetic fields (0.1‐1 T)  small pulsed solenoid
The circular polarization of FERMI@elettra allows measuring the circular dichroism
unique and significant information about the magnetic properties of the particles
LDM beamline
Multi‐photon single and multiple ionization experiments with FERMI@elettra pulses
Seeding scheme has high photon energy precision and stability  facilitate multi
photon experiments where resonant conditions are sought.
Feasibility
Cross-section is 10-50-10-53 cm2 s.
We estimate count rates of 0.1 to
100 counts/sec, for a 20 mm spot.
Energy: 10‐40 eV.
Circular and linear polarization
required.
For molecules: similar requirements
L.A.A. Nikolopoulos et al., J. Phys. B: At. Mol. 34 ,545 (2002)
EIS beamline
C. Masciovecchio
Andrea Di Cicco, Roberto Gunnella (University of Camerino); Adriano Filipponi (University of L’Aquila); Renato Torre (LENS);
Giancarlo Ruocco, Tullo Scopigno (University of Rome); Francesco Sette (ESRF); Filippo Bencivenga, Daniele Cocco, Francesco
D’Amico, Riccardo Cucini, Angela Trapananti, F. Parmigiani (Sincrotrone Trieste)
The Sample Side
Short pulses with very high peak power
Dt ~ 100 fs ; Peak Power ~ 5 GW ; E ~ 100 eV
Non-equilibrium distribution of electrons
What happens to the Sample?
Converge (electron-electron & electron-phonon collisions) to equilibrium (Fermi-like)
During this complex dynamics atoms go through a relaxation process due to the dramatic
changes of the potential energy surface
The intensity of the FEL pulses will determine the process to which the sample will
undergo: simple heating, structural changes, ultrafast melting or ultrafast ablation
Temperature (eV)
1.0
TEMAX
0.10
0.8
0.08
0.6
0.06
Lattice
TLMAX
Electrons
0.4
0.2
0.0
0.0
0.2
0.3
0.4
Time (ps)
0.5
0.6
TLMAX
Dt, Peak Power, E,
Sample, Fluence, …..
0.04
0.02
0.00
0.1
TEMAX
TIMER
TIMEX
TIMER
EIS beamline - TIMER
TIME-Resolved spectroscopy of mesoscopic dynamics in condensed matter
Challenge: Study Collective Excitations in Disordered Systems
in the Unexplored w-Q region
Q (q)
Determination of the Dynamic Structure Factor: S(Q,w)
2
10
1
10
0
IXS
-1
10
-2
10
-3
BL30/21
IUVS
BL10.2
w (meV)
BLS
10
INS
macro-scale nano-scale
10 -4 -3
10
-2
10
w = cs·Q
10
-1
10
0
10
Q ( nm -1 )
atomic-scale
1
10
10
q
2
Why Disordered Systems ?
Unsolved problems in physics
Condensed matter physics
Amorphous solids
What is the nature of the transition between a fluid or regular solid and a glassy phase? What are the
physical processes giving rise to the general properties of glasses?
High-temperature superconductors
What is the responsible mechanism that causes certain materials to exhibit superconductivity at
temperatures much higher than around 50 Kelvin?
Sonoluminescence
What causes the emission of short bursts of light from imploding bubbles in a liquid when excited by
sound?
Turbulence
Is it possible to make a theoretical model to describe the statistics of a turbulent flow (in particular, its
internal structures)? Also, under what conditions do smooth solution to the Navier-Stokes equations
exist?
Glass is a very general state of condensed matter  a large variety of systems can be
transformed from liquid to glass
The liquid-glass transition cannot be described in the framework of classical phase
transitions since Tg depends on the quenching rate  one cannot define an order parameter
showing a critical behaviour at Tg
The debate on V-SiO2 sound attenuation
IXS and IUVS data in the ~ 0.1 - 1 nm-1 region for Vitreous Silica
The understanding of collective dynamics nature in glasses at the nanoscale is still debated
P. Benassi et al., PRL 77, 3835 (1996)  Existence of propagating
excitations at high frequency
SiO
2
S(Q,w) (arb. units)
M. Foret et al., PRL 77, 3831 (1996)  They are localized above ~ 1 nm-1
T = 1075 K
-1
F. Sette et al., Science 280, 1550 (1998)  They are acoustic-like
Q = 1.6 nm
G. Ruocco et al., PRL 83, 5583 (1999)  Change of sound attenuation mechanism at 0.1-1 nm-1
B. Ruffle´ et al., PRL 90, 095502 (2003)  Change is at 1 nm-1
C. Masciovecchio et al., PRL 97, 035501 (2006)  Change is at 0.2 nm-1
W. Schirmacher et al., PRL 98, 025501 (2007)  Model agrees with Masciovecchio et al.
B. Ruffle´ et al., PRL 100, 015501 (2008)  Shirmacher model is not correct
-10
0
w (meV)
10
Thermal Conductivity, Excess in the V-DoS (Boson Peak), Specific Heat
European Research Council
ERC Starting Grant
Research proposal
TIME-Resolved Spectroscopy of Nanoscale Dynamics in
Condensed Matter Physics
Funded Grant: 1.8 M€
10 2
IXS
BLS
10 1
TIMER
Duration: 5 years
Start: June 2008
Solution: Free Electron Laser based
Transient Grating Spectroscopy Esignal
IUVS
w (meV)
10 0
Q(l,q)
BRISP
Epump
10-1
q
INS
10-2
Epump
10-3
10-4
10 -3
10 -2
10 -1
10 0
-1
Q ( nm )
10 1
10 2
Eprobe
F(Q,t)  Intermediate Scattering Function
TIMER - The Technique in Detail
Excitation Pulses
Sample
pulse
qs
Diffracted
Probe Pulse
Splitter
Induced Standing Wave
(Transient Grating)
Delayed Probe Pulse (Phase Matching)
Standing Wave Periodicity
x = 2p/Q
Q = 2kosin qs/2
Density Modulation Amplitude Monitored in Time by the Probe Pulse
F(Q, t)
The Spectrum
Optical absorption  Temperature Grating Time-dependent Density Response
(driven by thermal expansion)
S(t)
S(t)  ( cost – F(Q,t))
Sound waves region
Thermal
region
 region
Glycerol T=205 K
H2O
2 nm-1
1600
800
0
1.6
F(Q,t) (a.u.)
S(Q,w) (a.u.)
2400
0.8
0.0
-0.8
-10
-5
0
w (meV)
5
10
1
10
t (ps)
100
Typical Infrared/Visible Set-Up
M
Delay Line
(only for pulsed probe)
DM
l1
Probing CW (or pulsed) laser beam
l2=2l1
Excitation pulsed laser beam
Phase Control (Heterodyne)
Beam stop (Homodyne)
Neutral Filter (Heterodyne)
Eex1
EL
M
DOE:
Phase Mask
APD
Sample
Epr
AL1
Eex2
AL2
Es (Homodyne)
EL+Es (Heterodyne)
Challenge: Extend and modify the set-up for UV Transient Grating Experiments
The VUV Set-Up
FEL
pulse
1st harmonic l0
Grating
~5°
Laminar grating (~20% in ± 1 order)
3rd harmonic (~ 2%)
l1 = l0/3
~5°
~5°
CCD camera
Delay line
(ML mirrors, 3-meter long)
TIMER
ML mirrors
R&D, design and prototyping (12/2009)
2qs
2qs
Construction and installation (06/2010)
Commissioning (12/2010)
User operation (06/2011)
Sample
Other Possible Experiments
Heat Transport, Diffusion phenomena, Flow Studies, Concentration Grating, Electronic
Energy Transfer, Photochemical Reactions, Optical Damage ………………
H. J. Eichler et al., J. Appl. Phys. 44, 5455 (1973)
Spin Dynamics
TG can excite Spin Waves using orthogonal polarization
Spin Diffusion and Relaxation
in a 2-dim. Electron Gas
HHG in a Gas Jet
The harmonic signal encodes structural information on the orbital  full reconstruction
“......High harmonic transient grating spectroscopy can be extended to all forms of
molecular excitation and to weak resonant excitation......”
EIS beamline - TIMEX
Going Extreme with TIMEX: Warm Dense Matter (WDM), ultrafast heating
and melting, study of the dynamics of melting and nucleation
The phase diagram of carbon is poorly understood A. Ludwig, Z. Electrochem. 8, 273 (1902)
Pioneering Femtosecond Experiment
D. H. Reitze et al., PRB 45, 2677 (1992)  N. Bloembergen, Nature 356, 110 (1992)
“Femtosecond Experiments can be improved by using probe pulses in the VUV ...... to determine
individual Drude parameters....”  dielectric function e
Time-Resolved X-Ray Abs Spectroscopy
Hypothetical phase diagram of Carbon
20
Pressure (GPa)
J. N. Glosli et al., PRL 82, 4656 (1999)
High r liquid
15
Diamond
“ .. mixture of the two coexisting liquid
phases or in a supercritical fluid.....”
10
A. Cavalleri et al., EPL 57, 281(2002)
5
Low r liquid
Graphite
0
0.0
3
S. L. Johnson et al., PRL 94, 057407 (2005)
3
3
3
2.0x10 4.0x10 6.0x10 8.0x10 1.0x10
Temperature (K)
4
Long Times (t > 100 ps), Tamped sample
EIS beamline - TIMEX
Use the FEL Tunability to measure a XANES spectrum
Detector
0.8
Pulsed Laser
Si foil
Trasmission (0.2 mm)
0.7
FEL 3rd harmonic
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Jitter may be kept ~ 30 fs
60
80
100
E [eV]
120
140
Conclusions
Beamline for Magnetism - under evaluation (F. Parmigiani)
Beamline for THz Spectroscopy - under evaluation (S. Lupi)