| Budget Amount *help |
¥9,800,000 (Direct Cost: ¥9,800,000)
Fiscal Year 2004: ¥4,800,000 (Direct Cost: ¥4,800,000)
Fiscal Year 2003: ¥5,000,000 (Direct Cost: ¥5,000,000)
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| Research Abstract |
We have recently developed a novel preparation method of organic nanoparticles, where microcrystalline powder suspended in a poor solvent was converted into the nanoparticle colloidal solution by intense pulse laser irradiation. In this project, we have applied this method to several organic dyes as follows : Benzidine Yellow, Oralith Brilliant Pink R, Deep Red, quinacridone(QA), and aluminum chloride phthalocyaninec), Vanadil phthalocyanine, and examined the effect of laser pulse duration, intensity, and wavelength on the particle size.
When using nanosecond pulse YAG laser, stable colloidal solutions of nanoparticles were obtained at certain laser fluence and their size was about 50 nm for all compounds. In the case of QA, the crystalline phase and the mean size were changed by tuning the intensity and wavelength of laser pulses. On the other hand, their size was reduced into a 10 nm order by using femtosecond laser. This particles size have not bee achieved with other preparation methods such as mechanical grinding.
We also examined the nanoparticle formation processes and the mechanism by means of steady and time-resolve spectroscopic methods, and demonstrated that nanoarticle formation can be ascribed in terms of photo-thermal laser ablation mechanism. The obtained dependence of particle size on the pulse duration, intensity, and wavelength of laser was discussed on the bases of ultrafast laser heating of organic solid and the competitive cooling process through thermal diffusion into poor solvent.
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