Bench tests for microscopic theory of Raman scattering in powders of disordered nonpolar crystals: Nanodiamonds and beyond

Journal of Raman Spectroscopy. 2021. Vol. 52. No. 11. P. 1847–1859.

Yashenkin A., Utesov O., Koniakhin S.

Recent Raman data on nanocrystallite arrays are revised within the microscopic
theory for Raman peaks positions and broadening (linewidth). The theory
combines the elasticity theory-like approach for optical phonons used in
order to evaluate the Raman peaks structure and the Green's function method
applied for the phonon lines broadening. These theories are supported by the
atomistic calculations within the dynamical matrix method for optical
phonons and by the bond polarization model used to calculate the Raman
intensities. The experimental data on four various nanopowders are analyzed
with the use of this theory. The large width of the Raman peak in
nanoparticles as compared with the corresponding peak in bulk materials and
the width inverse dependence on the particle size previously observed by other
researchers are explained within the framework of the theory. It is shown that
the theory is capable to extract confidently from the Raman data four important
microscopic characteristics of the nanopowder including the mean particle
size, the variance of the particle size distribution function, the strength of
intrinsic disorder in the particle, and the effective faceting number that parameterizes
the particle shape.

Keywords: ширина линии, Raman scattering, Рамановское рассеяние, дефекты структуры, nanoparticles, Наночастицы, optical phonons, linewidth, lattice defects, оптические фононы