Study Of Fluorescence Spectra Of Starch

Graft copolymer of natural polymer is a kind of synthetics that could be synthesized through natural polymers activated to be free radicals by initiator chainreact with unsaturated monomers. Free radical is a group of one or more than one unpaired electrons stayed high energy excited state which molecule induced by physical or chemical factors produce. There are two main means to detect content of free radicals at present time. But the two means can't apply in detecting content of free radicals in the reaction at any time, so automation of starch graft copolymerization can't realize. Free radicals produced in graft copolymerization of natural high polymer are of the luminescence character, which may make it realistic to achieve detection, monitoring and automation of starch graft copolymerization. To achieve this purpose, first the mechanism of chemiluminescence producing by free radicals in graft copolymerization of natural polymer must be studied. However, the most fundamental work is to study fluorescence spectra of starch which is a representative substance of Graft copolymer of natural polymer.In this paper, fluorescence of starch itself excited by UV light using molecule fluorescent spectroscopy is studied to lay the foundation for studying the mechanism of chemiluminescence producing by free radicals. For the first time, fluorescence spectra of starch are detected through experiments. Starch doesn't dissolve in water and general organic reagents. So all of experimental analysis in this paper use starch suspension as sample. The experimental results indicate that starch-water suspension excited by 230nm to 280nm UV light can emit fluorescence ranged from 300nm to 450nm but peak wavelength varies with exciting light. When exciting light is between 260nm and 280nm, peak wavelength is always about 339nm. Furthermore, the physical mechanisms of fluorescence emission of starch are analyzed and expounded. It is considered that this fluorescence come from the transition from nonbonding namely n electrons in the hetero-atom (O) of the functional group ( C - O-C) called ether linkage to the antibonding orbitalσ~*.Starch dissolves in dimethylsulfoxide but still exists in it as very fine granulation. Dimethylsulfoxide has double bond and has strong absorption of some specified band of UV light, which is bad to detect starch's absorption spectra and worst to detect its fluorescence spectra. Starch in water takes on turbid state. But Absorption law namely Beer-Lambert law definite demand that optical properties of solution are...