Circular Dichrosim Of Chiral Gold Nanoparticles

Chiral gold nanomaterials have attracted tremendous interest due to their innovative basic understanding and potential applications in optics,catalysis and sensing.The main research objects of chiral gold nanomaterials are various types of nanostructures,including chiral complexes formed by achiral nanostructures induced by chiral molecules,chiral assemblies composed of several chiral nanomaterials with chiral molecules as templates,and asymmetrically grown helical nanostructures.The main research direction is the circular dichroism and related applications.Circular dichroism of chiral substances is mainly studied by circular dichroism spectrum,which is obtained by theoretical calculation,simulation or instrument measurement and the information reflected in the spectrum is analyzed.However,the experimental circular dichroism spectrum usually reflects the collective average result of a large number of chiral substances in solution,and can not reflect the circular dichroism of individuals.Many special properties of individuals will disappear in the circular dichroism spectrum due to the strong average effect.Scanning circular dichroism microscope detects extremely weak signals by modulating the polarized light at high frequencies.Single-point angle scanning and micro-area imaging are performed for the differential extiction of chiral substances to the left-hand and right-hand circular polarized light in a certain region using different detection wavelengths to analyze the circular dichroism of a single chiral nanostructure in the region.When the detection wavelength covers a sufficiently wide spectral range,a single chiral nanostructure circular dichroism spectrum can also be obtained and compared with a solution containing a large number of homogeneous structures to analyze its special properties.In this thesis,we analyzed the mechanism of optical chirality of achiral gold nanoparticles induced by chiral molecules and calculated the corresponding circular dichroism.The enhancement effect of surface plasmons on circular dichroism was found.We synthesis gold nanoparticles with a diameter of 15 nm,and L-cysteine was used to induce optical chirality of gold nanoparticles.The enhancement effect of cash nanoparticles on L-cysteine circular dichroism at 520 nm resonance peak of plasma exciton in circular dichroism spectrum measured from sample solution was found.In this thesis,scanning circular dichroism microscope with variable detection wavelength is used for the angle scanning experiment of single helical gold nanoparticles and the microscopic imaging experiment of multiple helical gold nanoparticles in a certain region.The signal response of multiple particles at different detection wavelengths is obtained,and the spectrum of each helical gold nanoparticle in the region is measured.