高ＩＦ論文受理をめざした光ナノテクノロジー研究ネットワーク形成

We made various attempts to publish high impact factor papers. Here we describe such efforts
and research activities carried out in fiscal year 2010. As a research, pulsed laser-induced
morphological transformation and size-reduction of colloidal gold nanoparticles in the aqueous
phase were investigated using transient absorption spectroscopy and transmission electron
microscopy (TEM). Femtosecond laser-induced fragmentation of gold nanoparticles within 100
ps after the laser pulse is interpreted in terms of the Coulomb explosion mechanism. On the
other hand, nanosecond laser-induced size-reduction of gold nanoparticles is in good agreement
with the photothermal evaporation mechanism that is based on heating of particles to
temperatures above the boiling point of gold (3100 K). Here, the experimentally observed
fragmentation thresholds were well-reproduced by simulations based on electron and lattice
temperature models and by considering the dissipation of heat into the surrounding medium. The
numerical method described herein has the advantage of identifying the fragmentation
mechanism by considering pulse duration- and energy-dependent thresholds.