Twist-Dependent Raman and Electron Diffraction Correlations in Twisted Multilayer Graphene

Nikita Gupta; Sunil Walia; Umesha Mogera; Giridhar U Kulkarni

doi:10.1021/acs.jpclett.0c00582

Twist-Dependent Raman and Electron Diffraction Correlations in Twisted Multilayer Graphene

J Phys Chem Lett. 2020 Apr 16;11(8):2797-2803. doi: 10.1021/acs.jpclett.0c00582. Epub 2020 Mar 25.

Authors

Nikita Gupta¹, Sunil Walia^{2

3}, Umesha Mogera¹, Giridhar U Kulkarni¹

Affiliations

¹ Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India.
² Centre for Nano and Soft Matter Sciences, Jalahalli, Bangalore 560013, India.
³ Manipal Academy of Higher Education, Manipal 576104, India.

PMID: 32191478
DOI: 10.1021/acs.jpclett.0c00582

Abstract

Twisted multilayer graphene (tMLG), in contrast to twisted bilayer graphene, offers a range of angular rotations for tuning the properties of the system. In this work, a turbostratic graphene system with a high degree of two-dimensional (2D) crystallinity is chosen to represent tMLG. We have investigated the distribution and population of twist angles from distributed sextets in electron diffraction (SAED) patterns with the collective Raman behavior at the same locations. A descriptor, termed the turbostratic factor, was calculated on the basis of angular spacings in SAEDs, to account for their distribution; the greater the spread, the higher the turbostratic factor. Raman spectra have revealed that the turbostratic factor remains low (∼0°) for a graphitic region with a low 2D to G intensity ratio (I_2D/I_G) and increases rapidly at higher I_2D/I_G values, saturating at 60° for highly turbostratic systems. Relating the intensities associated with the sextets and I_2D/I_G values, we found the maximum achievable value of I_2D/I_G to be 17.92.