ABSTRACT
In this paper the cluster structures of [Zn-(CH3CH2OH)n]2+ have been investigated with spectroscopic experiment and theoretical calculation. According to the fluorescence spectroscopy experiments, the fluorescence peak of ethanol molecules was found between 275~330 nm. A new peak appeared between 350~380 nm after the metal ions (Zn2+) was added into ethanol solution due to the generation of new clusters of molecules, and the original fluorescence peak of ethanol molecules became weak owing to the destroyed structure of ethanol molecules induced by Zn2+. The cluster structures of Zn2+ in water solution were investigated by using different methods. By comparing the results, a more accurate and fast B3LYP method of DFT was found and applied to optimize the possible structures of [Zn-(CH3CH2OH)n]2+. The results suggested that the first solvation shell of the system is up to six ethanol molecules, and thermodynamic parameters also shows the six kinds of molecular clusters which are likely in the solution. Moreover compared the theoretical fluorescence spectroscopy with experimental fluorescence spectroscopy, new clusters [Zn-(CH3CH2OH)n]2+ have been generated, with [Zn-(CH3CH2OH)n]2+(n=1~3) as main constructions.
ABSTRACT
In the applications of single-walled carbon nanotubes (SWNTs), it is extremely important to separate semiconducting and metallic SWNTs. Although several methods have been reported for the separation, only low yields have been achieved at great expense. We show a separation method involving a dispersion-centrifugation process in a tetrahydrofuran solution of amine, which makes metallic SWNTs highly concentrated to 87% in a simple way.
