Phonon spectroscopy by inelastic x-ray scattering

Abstract

The present synchrotron sources with brilliant x-ray beams, due to high photon fluxes, small source sizes and high collimation, have revolutionized x-ray physics.Enormous progress has been initiated in all established x-ray methods, with the aim of the development of new types of spectroscopy. This is particularly true for the spectroscopy of the dynamics in condensed matter. Meanwhile, there are two powerful x-ray methods with very high-energy resolution available for the study of low energetic excitations like phonons.This review summarizes the developments of these methods focusing on these instrumental developments of the spectrometers using either crystal optics in close-to-backscattering geometry or nuclear resonant techniques.Applications to measurements of phonon dispersion curves and of phonon density of states in ordered and disordered solids and in liquids are presented. It is shown how x-ray results are stimulating improvements in the theoretical approaches to the dynamics. New insights into the dynamics of liquids are discussed.The sensitivities of the spectroscopies allow the study of vibrational behaviour in very small amounts of material even in nanometre-sized thin films or particles. We can already analyse the phonon spectrum of a monolayered nuclear resonant isotope. Prospects of the techniques are also demonstrated.

Lattice dynamics of stishovite from powder inelastic X‐ray scattering

“…Introduction of the ODF to the sampling procedure was not necessary in case of stishovite. For the prediction of scattering intensities for individual phonon branches the CASTEP code output was employed as an input to scripts operating under Mathcad# computing the dynamical structure factor, S(Q, E), using standard formalism [Burkel, 2000]. Diffraction-derived thermal parameters were implemented [Kirfel et al, 2001].…”

Lattice dynamics in Bi2Te3and Sb2TeBessas1, Sergueev2, Wille3 et al. 2012Phys. Rev. B

“…12,13 However, access to the full density of phonon states (DPS) is feasible only by inelastic neutron 14 or x-ray scattering. 15 For most chalcogenides, due to structural complexity and formation of antisite defects, discussed, e.g., in Ref. 16, it is rather difficult to grow large single crystals for measuring phonon dispersion curves.…”

Experimental techniques of high-resolution inelastic X-ray scattering measurements for supercritical metallic fluids at high temperature and high pressure using synchrotron radiation at SPring-8

“…Information on collective and individual atomic motions can be obtained from INS by analyzing coherent and incoherent components of the dynamic structure factor, S(Q, E), where Q and E are momentum and energy transfer, respectively. In the last five years of the previous century, it became possible to use x-rays, instead of neutrons, as a probe of atomic dynamics (IXS instead of INS) [1,2], especially in disordered materials [3]. IXS is different from INS in the matter that the incoherent cross-section for x-rays only becomes large at high (> eV) energy transfers due to the small electron mass, so the IXS spectrum is entirely coherent and reflects the collective dynamics.…”