Brillouin Scattering With Simultaneous X-Ray Diffraction at GSECARS, Advanced Photon Source: Toward ...
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Brillouin Scattering With Simultaneous X-Ray Diffraction at GSECARS, Advanced Photon Source: Toward Determination of Absolute Pressure Scales. Jay Bass 1 Stanislav Sinogeikin 1,2 Dmitry Lakshtanov 1 Carmen Sanchez-Valle 1 Vitali Prakapenka 2, Guoyin Shen 2,3 Jean-Philippe Perrillat 1

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Brillouin Scattering With Simultaneous X-Ray Diffraction at GSECARS, Advanced Photon Source: Toward Determination of Absolute Pressure Scales

Jay Bass1

Stanislav Sinogeikin1,2

Dmitry Lakshtanov1

Carmen Sanchez-Valle1

Vitali Prakapenka2,

Guoyin Shen2,3

Jean-Philippe Perrillat1

Jingyun Wang1

Bin Chen1

1 University of Illinois at UC, Geology Dept.

2 GSECARS, The University of Chicago

3 HPCAT, Advanced Photon Sourse, Argonne National Laboratory

4 Carnegie Institution of Washington, Geophysical Laboratory

Fall AGU 2006


Brillouin Scattering with synchrotron X-rays at the APS GSECARS, Advanced Photon Source: Toward Determination of Absolute Pressure Scales

Elasticity Grand Challenge

COMPRES Infrastructure Development Project

Measure sound velocities and density simultaneously

“Absolute” or internally consistent Pressure Scales

Zha et al., Brillouin on MgO (PNAS, 2000)

Isothermal bulk modulus

(volume measurements)

Adiabatic elastic moduli

(velocity measurements)


Phase Transitions: Stishovite - CaCl GSECARS, Advanced Photon Source: Toward Determination of Absolute Pressure Scales2


Stishovite - CaCl GSECARS, Advanced Photon Source: Toward Determination of Absolute Pressure Scales2 : Brillouin scattering velocities


Brillouin scattering

Platelet (symmetric) geometry GSECARS, Advanced Photon Source: Toward Determination of Absolute Pressure Scales

Vi = / 2sin (*/2)

Brillouin scattering

  • Acoustic waves present in a solid due to thermal motion of atoms

  • Laser lightinteracts with phonons (or density / refractive index fluctuations) and is scattered with Doppler shifted frequency 

  • Brillouin shift is proportional to acoustic velocity

    Vi = / 2n*sin (/2)


Schematic diagram of the Brillouin system installed at sector 13-BMD (GSECARS) at APS

Sinogeikin et al.,Rev.

Sci. Instr. 77, 2006


Schematic diagram of the Brillouin system installed at sector 13-BMD at APS (Lower Tier)

Motorized translation components (controllable from outside the hatch, blue boxes): HMTS - horizontal motorized translation stage; VMTS - vertical motorized translation stage; MLFA - motorized laser focusing assembly; MSCA - motorized signal collecting assembly; SPOA - sample positioning and orientation assembly; SL-LB - sample light / light block.

Observation / feedback elements (red boxes): VC - video camera; BT - beam target.

X-ray components: MAR - MAR Imaging plate; XBS - X-ray beam stop; CS - cleanup slit.



X ray image and integrated spectrum of single crystal nacl at ambient conditions
X-ray image and integrated spectrum 13-BMD GSECARSof single-crystal NaCl at ambient conditions


Single crystal nacl b1 at 30 gpa in dac in ne pressure medium

Ruby 13-BMD GSECARS

NaCl

Single

crystal

100 μm

Au+Pt+NaCl

Au+Pt+NaCl

Single crystal NaCl (B1) at ~30 GPa in DAC in Ne pressure medium

Schematic view of simultaneous Brillouin scattering and X-ray diffraction in DAC



Single crystal brillouin spectrum of nacl b1 and velocity distribution in 100 plane at 30 5 gpa
Single crystal Brillouin spectrum of NaCl (B1) GPa and velocity distribution in (100) plane at 30.5 GPa




Aggregate velocities of NaCl (B1) GPa as a function of density


Absolute equations of state pressure scale
“Absolute” equations of state / pressure scale GPa

Isothermal bulk modulus (volume measurements)

Adiabatic elastic moduli (velocity measurements)

We measure Ks as a function of volume directly. The problem is to convert KS to KT at high pressure, e.g. we need to know volume dependence of a and g.

Possible models/assumptions:


Conclusions
Conclusions GPa

  • We simultaneously measured single crystal (and aggregate) elastic moduli of NaCl (B1) with Brillouin spectroscopy and density with angle dispersive X-ray diffraction to 30.5 GPa.

  • At high pressure NaCl exhibits extreme elastic anisotropy, which is >3 times higher than that at ambient conditions.

  • Above ~17 GPa on approaching B1-B2 phase transition NaCl exhibits acoustic mode softening.

  • Above ~17 GPa the density – velocity relations deviate from linearity and violate Birch’s law.

  • Acoustic softening indicates that B1-B2 phase transition in NaCl may be multi-step and of more complicated nature than it was previously thought.

  • Pressure calculated from measured bulk modulus and density is higher than that calculated from Decker EOS by ~ 3-5% at 30 GPa.


Acknowledgments
Acknowledgments GPa

  • NSF: Elasticity Grand Challenge

  • COMPRES: Infrastructure development project

  • GSECARS: Sector 13, Advanced Photon Source


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