Absorption and Rayleigh scattering and resonance Rayleigh scattering spectra of [HgX2]n nanoparticles

The composition and existing species of the reaction production of Hg and X (X= Cl, Br and I) under different conditions, and their absorption, Rayleigh scattering (RS) and resonance Rayleigh scattering (RRS) spectra have been studied. The results show that the products exist in the form of nanoparticles as [HgX2]n aggregates under suitable conditions, and their average diameters increase with the increase of X diameters. The diameters of [HgCl2]n, [HgBr2]n and [HgI2]n are less than 4 nm, equal to 9 nm and 70 nm respectively. There are bathchromic shifts gradually with the increase of X diameters in their absorption spectra. The absorption bands of [HgCl2]n and [HgBr2]n locate at ultraviolet region. However, the absorption band of [HgI2]n is obvious in visible light region. Among three particles, only [HgI2]n exhibits a strong RRS and its scattering peak is at 580 nm. The main reasons leading to the enhancement of resonance scattering are the large size of nanoparticle, the formation of the interface and the location of light scattering in the absorption band. There are three important factors affecting resonance scattering spectrum: the quanta colored effect and molecular absorption spectrum of [HgI2]n nanoparticle as well as instrumental factors which mainly include the light source’s emission spectral characteristics and the signal response curve of detector.