Spettroscopia Raman e Grandi Sorgenti
(Synchrotron Facilities)
Marco Milanesio
Dipartimento Scienze e Tecnologie Avanzate
Università del Piemonte Orientale, Alessandria, Italy
E-Mail: [email protected]
http://www.mfn.unipmn.it/~marcomi
Nuove Applicazioni della Spettroscopia Raman nei Minerali
Parma 12 Febbraio 2009
Raman e Mineralogia, Parma, 12 febbraio 2009
What is a synchrotron facility?
Storage ring producing high brilliance X-ray (10001000000 more intense than in normal diffractometers)
Marco Milanesio
Raman e Mineralogia, Parma, 12 febbraio 2009
2
Standard SNBL Beam line at ESRF
B-Hutch
A-Hutch
Optics A+B HRPD + XAFS
PD +Single
x-tal
Raman e Mineralogia, Parma, 12 febbraio 2009
Prep-lab
Typical business at synchrotron facilities :
The good news: Synchrotron allows
X-ray Powder
Diffraction (XRPD) in situ studies (down to ms time res.)
(a)
Environmental chambers are
used to condition the sample
environment: Temperature,
pressure, atmosphere,
irradiation, laser in situ
during XRPD
When a phase undergoes a
phase transition its
diffraction pattern changes
Marco Milanesio
Raman e Mineralogia, Parma, 12 febbraio 2009
4
IN SITU XRPD synchrotron facilities?
1) The availability of 3rd generation synchrotrons allowed the
use of XRPD experiments at in situ conditions.
2) The addition of an extra dimension, such as time or
temperature allowed the investigation of structural
properties during solid-state transformations
Template Burning inside TS-1 and Fe-MFI Molecular Sieves: An in Situ XRPD Study. Milanesio, M.; Artioli,
G.; Gualtieri, A. F.; Palin, L.; Lamberti, C.
J.
Am. Chem. Soc.; 2003; 125(47); 14549-14558
Marco Milanesio
Raman e Mineralogia, Parma, 12 febbraio 2009
5
Why Raman and synchrotron facilities?
Sometime overcame by Raman!!
The bad news: the limits of in situ XRPD
disordered moieties
light elements (Z < 4)
Marco Milanesio
gel phases
liquid phases
nanoparticles
surface reactivity
Raman e Mineralogia, Parma, 12 febbraio 2009
amorphous phases
evolved gas
6
Raman information
Raman spectroscopy can give complementary
information to XRPD, being extremely sensitive to small
structural
distortions,
to
changes
in
the
hydration/protonation states, to surface modifications and
to changes in the charge/defect distribution and shortrange ordering.
Raman e Mineralogia, Parma, 12 febbraio 2009
Why Simultaneous RAMAN/XRPD?
Because of the perfect space, time and reaction-coordinate
correlation between Raman and XRPD and no bias due to
different sample holder/conditioning modes
• Many non-simultaneous Raman-Xray diffraction/absorption
studies have been performed for their complementarities.
• In situ induced sample modifications with multiple external
stimuli such as:
–
–
–
–
–
•
Temperature and/or
Pressure and/or
UV or Visible Light, X-ray’s and/or
Oxidizing or reducing environments
….
On samples that show kinetic and non-reversible
behaviors on one or more of these stimuli
Difficult or impossible to synchronize
separate XRPD and Raman experiments 8
Marco Milanesio
Raman e Mineralogia, Parma, 12 febbraio 2009
The first example - Phase transitions of
isobutyl-silsesquioxane (SNBL@ESRF, July 2004)
XRPD: phase transition from the triclinic to rhombohedral
phase at 323 K
Raman spectroscopy: small variation of the peak at 775 cm-1
related to rotation of the side chain O-Si-C-C torsion angles
This case study allowed i) to test the first Raman/XRPD
implementation with a NIR laser (1064 nm) and ii) to
design the better setup for the permanent Raman
installation at the SNBL
Marco Milanesio
Raman e Mineralogia, Parma, 12 febbraio 2009
9
SNBL layout with Raman
A-Hutch
Optics A+B HRPD + XAFS
PD +Single
x-tal
Prep-lab
Excitation laser
Raman return
Raman e Mineralogia, Parma, 12 febbraio 2009
Raman
B-Hutch
The Experimental Set-up – Technical details
References on the simultaneous experiments
- More info: E. Boccaleri, F. Carniato, G. Croce, D. Viterbo, W.
van Beek, H. Emerich and M. Milanesio, In situ simultaneous
Raman/high-resolution X-ray powder diffraction study of
transformations occurring in materials at non-ambient
conditions, J. Appl. Cryst. (2007). 40, 684-693.
Raman e Mineralogia, Parma, 12 febbraio 2009
Possible multi-technique experiments at the SNBL…
Raman/XRPD
Raman/EXAFS
Raman/XRPD/EXAFS
Raman/XRPD/XAFS/Mass Spectroscopy
Raman/Single crystal XRD
Marco Milanesio
Raman e Mineralogia, Parma, 12 febbraio 2009
12
….. accessible non ambient conditions
Gas blower + Cryostream nitrogen blower:
from 80 to 1300 K
Helium cryostat down to 5-10 K
Diamond Anvil cell: from 0 to 50 GP
Lamp- and laser- induced excitation:
photo-reactivity
Gas pumping system: from vacuum to 30 bars
Marco Milanesio
Raman e Mineralogia, Parma, 12 febbraio 2009
13
Case study 1 - The stearate-hydrotalcite
(Mg/Al layered hydroxide) thermal treatment
and decomposition (almost no mineralogy!)
Example of application to a
low order synthetic
nanocomposite organicinorganic material –
conformational/chemical
sensitivity of Raman
Marco Milanesio
Raman e Mineralogia, Parma, 12 febbraio 2009
14
Case study 1 - XRPD
At 362 K phase transition
due to the swelling of the
layers
A new peak appeared at
2θ=0.81° (d=42.4 Å). Its
intensity increased up to 425
K and its 2θ moved to 0.72°
(d=48.2 Å).
Marco Milanesio
Raman e Mineralogia, Parma, 12 febbraio 2009
15
Case study 1 - Raman
The C-H stretching modes (2800-3000 cm-1) and the symmetric
and asymmetric C-C stretching modes (at 1044 and 1110 cm-1)
are sensitive to the changes in the trans-gauche
conformation of the CH2 units and to the packing of the
embedded phase.
Marco Milanesio
Raman e Mineralogia, Parma, 12 febbraio 2009
16
The phase transition characterization
Raman/XRPD  the conformational features of the organic
moiety and the structural rearrangement of the inorganic moiety
ΔT
31.5 Å
(XRPD
at RT)
45.0 Å
(XRPD)
At room temperature: all-trans stearate chains form an
inter-digitated bi-layer while (Raman).
At high temperature: the chains assume folded gauche
conformations and inter-digitation is reduced (Raman).
Marco Milanesio
Raman e Mineralogia, Parma, 12 febbraio 2009
17