Application of polarized Raman spectroscopy for determination of crystallographic orientation of metal-organic frameworks

Abstract

Polarised Raman spectroscopy technique has been widely used for the characterization of the composition and structure information of various materials since it is non-destructive. Raman spectroscopy has been established as one of the core experimental tools to study of isotropic and anisotropic two-dimensional materials. This method is used to determine information about the symmetry of vibrational modes, which is not always possible in Raman scattering measurements using unpolarized light. Furthermore, polarized Raman spectroscopy can reveal crystallographic orientation, molecular orientation distributions and azimuthal angle of materials in three dimensions.
In this work, we applied this method for the first time to study metal-organic frameworks DUT-8 (Ni, Co). Metal-organic frameworks are a new class of hybrid ordered porous materials. DUT-8 (Ni, Co) contains nickel and cobalt ions as coordinating metal ions and organic linkers. In addition, DUT-8 has the unique ability to transform its crystal structure under external factors. Polarized Raman spectra were obtained with parallel and cross-parallel polarizations of the incident and scattered radiation to study angular dependence of intensities of Raman spectra lines of microcrystals in the range 120-1750 cm-1. The ratios of opposite angular dependent lines intensities gave a 2-lobed characteristics with sample rotating, which was independent of the experimental conditions in the parallel-polarized configuration.
The results can be used for in situ determination of crystallographic orientation DUT-8 (Ni, Co) in different phases. The method can be also applied to similar materials.
The study was supported by the Russian Foundation for Basic Research, project No. 21-52-12018.

Speaker

Nina Slyusarenko
Siberian Federal University
Russia

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