High Pressure Workshop

Time-domain Brillouin scattering for 3D-imaging of texture, phase transitions, elastic and plastic properties of solids compressed in a diamond anvil cell

11 May 2026, 16:40

20m

Auditorium (WHGA) (PSI Villigen)

Talk

Speaker

Dr Andreas Zerr (LSPM-CNRS)

Description

Time-domain Brillouin scattering (TDBS) technique uses ultrafast laser pulses to generate coherent acoustic pulses (CAPs) and monitor their propagation through transparent samples. Local velocity of a CAP along depth of a sample (V_A, where A represents longitudinal (L) or transversal (T) sound velocity) is extracted from oscillating intensity of the probe light scattered by the CAP and interfering with that reflected by stationary interfaces [1]. Frequency of the oscillation, f_B, is given by the well-known equation used in classical Brillouin light scattering in the backscattering geometry: f_B=2 n V_A/ λ, where λ is the wavelength in vacuum of the probe laser beam and n the refractive index of the examined material at this wavelength. Spatial distribution of the f_B values can be extracted with micron and submicron resolution in lateral and axial directions, respectively. The latter capability of the TDBS technique permits measurement of single crystal elastic moduli, C_ij(P), of any transparent solid compressed in a diamond anvil cell (DAC) to Mbar pressures [2] including polycrystalline cubic phases not available at ambient conditions, e.g. high pressure phases [3, 4]. Similarly, shear modulus of an amorphous or of an isotropic polycrystalline solid, G( P), can be determined if its bulk modulus, B( P), is known [5]. In the case of elastically anisotropic solids, the TDBS technique provides 3D-images of texture of the polycrystalline samples including orientation of individual crystallites in space [6]. Finally, it permits 3D-monitoring of progress of phase transitions or chemical reactions to pressures accessible using the DAC technique [7]. Combination of the TDBS technique with high-resolution X-ray diffraction in a DAC provides a straight-forward way to an assumption-free high-pressure scale. A novel secondary pressure scale based on the f_B(P) dependence of the mixture of methanol and ethanol in the volume ratio 4:1 was already proposed and applied to measure pressure dependence of yield strength, σ_y(P), of this amorphous solid [5].

References:
1. Kuriakose M. et al., Ultrasonics 69, 259-267 (2016)
2. Zhang X. et al., J. Geophys. Res.-Solid Earth 128, e2022JB026311 (2023)
3. Raetz S. et al., Phys. Rev. B 99, 224102 (2019)
4. Xu F. et al., Appl. Phys. Lett. 125, 164102 (2024)
5. Hong C. et al., Phys. Rev. B 111, 184110 (2025)
6. Sandeep S. et al., J. Appl. Phys. 130, 053104 (2021)
7. Kuriakose M. et al., New J. Phys. 19, 053026 (2017)