Dichroism Of Thin-Layer Rhenium Disulfide And Single Self-Assembled Supramolecular Chiral Nanobelt

Two-dimensional materials have great prospects of application in nano-devices.Two-dimensional materials,such as black phosphorus and rhenium disulfide?ReS₂?,become hotspot in the application of nano-devices due to their in-plane anisotropy.The optical properties of anisotropic two-dimensional materials mainly reflect on the linear dichroism.Chiral molecules play a key role in biological science,synthetic and natural compounds,and even in the field of materials including liquid crystals.The circular dichroism of chiral molecules is the key to studying the optical properties of chiral molecules.There are many methods for the study of anisotropy materials,such as phase interferometry,angle-resolved polarization Raman spectroscope?ARPRS?,photothermal detection,reflectance difference microscopy and so on.These methods have some shortcomings for studying the optical anisotropy of two dimensional materials,for example,some have low signal to noise ratio,and some experimental optical paths are more complicated.Scanning polarization modulation microscope?SPMM?can realize high frequency modulation and demodulation of polarization.SPMM can quickly determine the crystalline orientation and quantitatively measure the birefringence or linear dichroism of two-dimensional materials at submicron-scale.SPMM can quantitatively measure the absorption and absorption difference of chiral molecules for the left-handed circularly polarized light and right-handed circularly polarized light,and then the dissymmetry factor is calculated.In this thesis,SPMM is used on studying dichroism of thin-layer ReS₂ and single righted-handed DPF-NCNST-DBD self-assembled supramolecular chiral nanobelt.Firstly,we performed differential reflectance and differential transmittance imaging of thin-layer rhenium disulfide by SPMM at 473 nm,532nm and 1064 nm.It was found that the optical anisotropy of thin-layer rhenium disulfide was stronger at 532 nm.It was found that the thicker the thickness,the optical anisotropy thin-layer ReS₂ was stronger.SPMM determined the crystalline orientation of thin-layer rhenium disulfide at 532 nm,which was consistent with the orientation determined by ARPRS.SPMM is not only can accurately determine the crystalline orientation,but also realize the visualization of thin-layer ReS₂.In this thesis,we measured absorption difference of the single self-assembled supramolecular chiral nanobelt between the left-handed circularly polarized light and right-handed circularly polarized light by SPMM at 473 nm.We calculated the absorption dissymmetry factor of 10^-2.We compared the dissymmetry factor of the self-assembled supramolecular chiral nanobelts with different thickness and got a conclusion of the thicker the sample,the larger the dissymmetry factor.Because the chiral interactions among the chiral molecules are stacked step by step and gathered together regularly,they formed a curved structure to release the chiral tension between the chiral molecules.Thereby,the helicity of the self-assembled chiral supramolecules is higher.