Preparation And Circular Dichroism Of Chiral Mercury Sulfide Nanocrystals

Chirality is a geometric property of describing that an object cannot overlap with its mirror image.Generally speaking,chirality is for chiral molecules,but the definition of chirality,which is usually used to describe the properties of molecules,can be applied to nanoscale objects to obtain chiral nanostructures.Inorganic nanocrystals in chiral nanostructures are of great significance.Inorganic nanocrystals have unique size or shape depending on physical and chemical properties,which provide a wide range of research and development possibilities in photonics,electronics,catalysis,biology and other fields.Mercuric sulfide is a typical semiconductor inorganic chiral crystal.It has two different crystal structures,one of which is chiral.Surface ligand induced synthesis is an effective method to prepare high quality chiral nanocrystals.In this paper,chiral mercuric sulfide nanocrystals with about 10-15 nm were synthesized by this method,and their circular dichroism was studied by optical imaging system.The circular dichroism of HgS nanocrystals was analyzed by numerical simulation.Chiral nanocrystals have unique chiral optical phenomena,among which circular dichroism is the most widely studied.The circular dichroism shows that the absorption of left-handed and right-handed circularly polarized light is different.The basic methods to study chiral optics include optical rotation spectrum,circular dichroism and circular dichroism fluorescence spectrum,but there are some shortcomings in these methods.In this paper,the circular dichroism of HgS nanocrystals is used to realize the circular dichroism imaging of HgS nanocrystals and the measurement of asymmetry factor at 540 nm wavelength.The influence factors of circular dichroism imaging in the system are explored,and Circular dichroism imaging of nanocrystalline aggregates at about 1?m and 100nm,and the order of asymmetry factor is 10^-2.The circular dichroism of the chiral absorption sphere model of mercury sulfide nanocrystals in air at nanoscale was studied using the classical method based on Maxwell's equations.Maxwell's constitutive equation of chiral media is used to calculate the absorption characteristics and circular dichroism of the chiral absorbent sphere.The circular dichroism spectra generated by two mechanisms of the chiral absorbent sphere with different radius are calculated and analyzed.The circular dichroism is generated from the chiral properties of HgS nanocrystals inside the chiral sphere and the near-field interaction between the surrounding environment and the boundary of the chiral medium sphere.It was found that the circular dichroism produced by both mechanisms was related to the radius of chiral absorbent spheres by changing the size of absorbent spheres.