Studies On The Theory And Experiment Of The Organic Nanoparticle Preparation By Laser Ablation

Metallic and semiconductor nanoparticles have become the focus of much attention because of their unique physical and chemical properties. Recent years different method to produce organic nanoparticles have been proposed by some scholars and they have found the organic nanoparticles also possess the notable property of size effect, so there has been a tendency to extend the study of nanoparticles from inorganic compounds to organic compounds. Comparison shows that laser ablation in aqueous solution is a simpler and easier method for producing organic nanoparticles and is better suited for organic compounds that are non-water soluble or water soluble resistant. We should also note that organic compounds in colloid solution can be directly obtained by this method, so it allows other organic solvents to be substituted with water in most applications of chemical industrial fields.In present dissertation, Systematical and experimental studies of the preparation of the organic dye - metal phthalocyanine nanoparticles by laser ablation in water were carried out. Lots of new experimental phenomena have been found and new technology for the enhancement to this method has been proposed. The main achievements are as below:1. The a and p crystalline forms of copper phthalocyanine (CuPc) nanoparticles have been fabricated successfully with the mean size of 100 nm. X ray diffraction patterns, UV-Vis absorption spectroscopy and Fourier-transform infrared spectroscopy have been used to analyze the crystalline structures of obtained CuPc nanoparticles. The results have shown that the crystalline structures of the a and P forms of CuPc have no change before and after laser ablation. It indicates that both a and (3 forms of CuPc are stable during laser ablation and laser ablation is a simple and efficiency method to fabricate the nanoparticles of above two forms of CuPc.in2. During the nanoparticles preparation of oxo(phthalocyaninato) vanadium (IV) (VOPc), It has been found that too long an irradiation time does not contribute to producing nanoparticles and their generation efficiency increases with a low solution temperature. We think the hydrophobic force in water is the main reason for nanoparticle reassociation, and it can decrease the production efficiency.3. Under the fluence of 50, 120 and 200 ml/cm2 the VOPc nanoparticles have been prepared by laser irradiation. Analysis of atom force microscope (AFM) shows the obtained nanopartilces possess the mean size of 55, 105 and 110 nm respectively. So the main size of obtained nanoparticles will increase with the laser fluence increasing.4. The mathematical model of photothermal mechanism in laser ablation has been proposed and the equation of ablation depth for single laser pulse has also been deduced.5. To prevent generated nanoparticles from reassociating we have performed experiments adding two kinds of ionic and nonionic surfactants into solution. We have found four characteristics of nanoparticle generation from adding surfactants to a solution regardless of the type of surfactant used. These characteristics are that: I.production efficiency increases; Instability is better after irradiation; HI.)ablation threshold needed to induce nanoparticle generation become lower; IV.)the mean size of the generated nanoparticles becomes smaller.6. It has been found that the crystalline structures of VOPc nanoparticles are controllable by changing the surfactant concentration. The nanoparticles in phase I will be fabricated in the condition of low surfactant concentration and phase II in high surfactant concentration. The transformation in the nanoparticles from phase I to phase II will be more faster when the surfactant concentration is higher than its critical micelle concentration (CMC). We think the thermal effect is the main reason for this transformation.IV7. In the aqueous solution the Q band of iron phthalocyanine (FePc) nanoparticles possess the properties of blue shift and re...