| Budget Amount *help |
¥12,290,000 (Direct Cost: ¥11,000,000、Indirect Cost: ¥1,290,000)
Fiscal Year 2007: ¥5,590,000 (Direct Cost: ¥4,300,000、Indirect Cost: ¥1,290,000)
Fiscal Year 2006: ¥6,700,000 (Direct Cost: ¥6,700,000)
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| Research Abstract |
(1) Devise for Enhanced Light Absorption
A fully conductive bulk Ag film, when sputter-gfown on a substrate directly exposed to the glow dischargeplasma, developed unique nanoscale surface roughness features that caused distinct single-nanoparticle-liksurface plasmon (SP) scattering. This highly reflective SP scatterer, capable to give substantial light scattering with minor surface roughness, functioned as a superior reflector in a novel nanospaced trilayer structure for high-efficiency light-absorption enhancement. The small base (intrinsic) absorptance less than 0.3% of a thin light absorber layer atop was thus easily enhanced by more than 10 times in a wide range of the visible region.
(2). Photo-Electric Conversion Based on Enhanced Light Absorption System
The above system for enhanced light absorption was succefully applied to photoelectric conversion with a thin layer of cyanine dyes as the otherwise weak light absorber. The overall photocurrent generation efficiency was enhanced b
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y 10 times or more, in agreement with the improved light harvesting efficiency.
(3). Laser Synthesis of Metal Nanoparticles
The fragmentative decomposition of ketone-suspended Ag2O micropowders (most preferably in acetone), induced by 1064 nm nanosecond laser irradiation as a single-pulse event at the required minimum laser fluence as low as □0.1J/cm2, proved to offer a highly productive pathway to novel Ag nanoparticles (AgNPs) with many unique properties. The maximum NP production rate reached 2.5mg/min at the input laser power of only ~0.5W, and the product AgNPs, typically 10-20nm in diameter, exhibited excellent dispersity in ketone without any intentional addenda, thus being self-stabilized for concentrations up to ~5wt % (in acetone) or to more than 20wt% (in γ-butyrolactone).
(4) Surface-Plasmon-Induced Enhanced Emission
We found that closely packed submicro-scale Ag islands (each ~370nm across and~90nm in height on the average) produced not only extremely short-range fluorescence enhancement for rhodamine dye (RhB) placed only ~1nm away from the metal surface, but also a novel, long-range enhancement for the same dye for the metal-molecule distance up to ~50nm. The net enhancement factor for the spin-coated RhB, with a fluorescence quantum yield of ~2% in the absence of Ag islands, was as high as~20-folds at the metal洋olecule distance of ~30nm. Less
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