Investigating through Raman spectroscopy simulations, the magic angle in twisted bilayer graphene, and the interaction of DNA nucleotides with 2D-materials (Gr, BP)
Younes Akabli,
University Mohammed VI Polytechnic (Institute of Applied Physics)
IAP Physics Seminar Series will occur on Tuesday 01 October, at 11:15 at the UM6P campus (Ryad 8, 1st floor).
Abstract:
Twisted bilayer systems of 2D materials have generated great recent interest due to their ability to create new tunable electronic behavior. It was found that twisted bilayer graphene (tBLG) has shown unconventional superconductivity for some specific twist angle so called “the magic angle”. Raman spectroscopy is a fundamental tool to study these systems since the Raman response is hugely dependent on the twist angle. In this work, the non-resonant Raman spectra of twisted bilayer graphene has been calculated for different twist angle values. The spectra reveal the emergence of additional Raman active modes compared to AB stacked bilayer graphene. The effect of twist angle is investigated by analyzing the Raman active modes and their associated eigen displacement. The precise association of these Raman modes positions with the twist angle will provide precise data for an accurate determination of the structural properties. On the other hand, at low twisting angles, three localized modes emerge, indicating the reconstruction of the geometrical moiré pattern. In this regime, the layers adjust to minimize the AA-stacking regions, leading to a more stable configuration.
Surface enhanced Raman scattering (SERS) is a fingerprint spectral technique whose performance is highly dependent on the physicochemical properties of the substrate materials. In the case of 2D materials, chemical enhancements driven by interfacial charge transfer are often major contributors to the overall SERS behavior, distinguishing them from traditional substrates based on plasmonic metals. Although the change of the substrates structural compositions and electronic properties affects the enhancement. Here we study the Raman enhancement effect on graphene (Gr) and Black phosphorene (BP), by using DNA nucleotides as a probe. We found that BP enhances the Raman signal better than Gr. To understand the origin of this enhancement, we examined the anisotropic behavior of BP, which leads to the increase of the probe molecules dipole moment and alters their Raman tensor symmetry more compared to graphene. Additionally, we examined the electronic behavior and found that the charge transfer is more significant in BP than the one in Gr. This study highlights the potential of Black Phosphorene as a promising platform for biosensor applications, paving the way for advances in biomolecular sensing.
Biography:
Younes Akabli holds a master’s degree in computational physics from UM5R in Rabat, Morocco. He is currently a Ph.D. student at the Institute of Applied Physics at UM6P in Benguerir, Morocco. His research focuses on simulating Raman spectroscopy of the systems based on two-dimensional materials.
Localization: Ryad 8, 1st Floor.