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Raman e Mineralogia, Parma, 12 febbraio 2009 Spettroscopia Raman e Grandi Sorgenti (Synchrotron Facilities) Marco Milanesio Dipartimento Scienze e Tecnologie.

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Presentazione sul tema: "Raman e Mineralogia, Parma, 12 febbraio 2009 Spettroscopia Raman e Grandi Sorgenti (Synchrotron Facilities) Marco Milanesio Dipartimento Scienze e Tecnologie."— Transcript della presentazione:

1 Raman e Mineralogia, Parma, 12 febbraio 2009 Spettroscopia Raman e Grandi Sorgenti (Synchrotron Facilities) Marco Milanesio Dipartimento Scienze e Tecnologie Avanzate Università del Piemonte Orientale, Alessandria, Italy Nuove Applicazioni della Spettroscopia Raman nei Minerali Parma 12 Febbraio 2009

2 Raman e Mineralogia, Parma, 12 febbraio 2009Marco Milanesio 2 Storage ring producing high brilliance X-ray ( more intense than in normal diffractometers) What is a synchrotron facility?

3 Raman e Mineralogia, Parma, 12 febbraio 2009 Standard SNBL Beam line at ESRF Optics A+B HRPD + XAFS PD +Single x-tal B-HutchA-HutchPrep-lab

4 Raman e Mineralogia, Parma, 12 febbraio 2009Marco Milanesio 4 The good news: Synchrotron allows X-ray Powder Diffraction (XRPD) in situ studies (down to ms time res.) Typical business at synchrotron facilities : When a phase undergoes a phase transition its diffraction pattern changes Environmental chambers are used to condition the sample environment: Temperature, pressure, atmosphere, irradiation, laser in situ during XRPD (a)

5 Raman e Mineralogia, Parma, 12 febbraio 2009Marco Milanesio 5 1) The availability of 3 rd 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 IN SITU XRPD synchrotron facilities? 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);

6 Raman e Mineralogia, Parma, 12 febbraio 2009Marco Milanesio 6 The bad news: the limits of in situ XRPD amorphous phases evolved gas gel phases liquid phases nanoparticles surface reactivity disordered moieties light elements (Z < 4) Why Raman and synchrotron facilities? Sometime overcame by Raman!!

7 Raman e Mineralogia, Parma, 12 febbraio 2009 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 short- range ordering. Raman information

8 Raman e Mineralogia, Parma, 12 febbraio 2009Marco Milanesio 8 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-rays and/or –Oxidizing or reducing environments –…. On samples that show kinetic and non-reversible behaviors on one or more of these stimuli 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 Difficult or impossible to synchronize separate XRPD and Raman experiments

9 Raman e Mineralogia, Parma, 12 febbraio 2009Marco Milanesio 9 The first example - Phase transitions of isobutyl-silsesquioxane 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

10 Raman e Mineralogia, Parma, 12 febbraio 2009 SNBL layout with Raman Optics A+B HRPD + XAFS PD +Single x-tal B-HutchA-HutchPrep-lab Raman Excitation laser Raman return

11 Raman e Mineralogia, Parma, 12 febbraio 2009 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,

12 Raman e Mineralogia, Parma, 12 febbraio 2009Marco Milanesio 12 Possible multi-technique experiments at the SNBL… Raman/EXAFS Raman/XRPD/EXAFS Raman/XRPD/XAFS/Mass Spectroscopy Raman/Single crystal XRD Raman/XRPD

13 Raman e Mineralogia, Parma, 12 febbraio 2009Marco Milanesio 13 ….. accessible non ambient conditions Helium cryostat down to 5-10 K Diamond Anvil cell: from 0 to 50 GP Lamp- and laser- induced excitation: photo-reactivity Gas blower + Cryostream nitrogen blower: from 80 to 1300 K Gas pumping system: from vacuum to 30 bars

14 Raman e Mineralogia, Parma, 12 febbraio 2009Marco Milanesio 14 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 organic- inorganic material – conformational/chemical sensitivity of Raman

15 Raman e Mineralogia, Parma, 12 febbraio 2009Marco Milanesio 15 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).

16 Raman e Mineralogia, Parma, 12 febbraio 2009Marco Milanesio 16 Case study 1 - Raman The C-H stretching modes ( 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 CH 2 units and to the packing of the embedded phase.

17 Raman e Mineralogia, Parma, 12 febbraio 2009Marco Milanesio Å (XRPD at RT) The phase transition characterization Raman/XRPD the conformational features of the organic moiety and the structural rearrangement of the inorganic moiety At room temperature: all-trans stearate chains form an inter-digitated bi-layer while (Raman) Å (XRPD) At high temperature: the chains assume folded gauche conformations and inter-digitation is reduced (Raman). ΔTΔT


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