No abstract

The hollow structure formation mechanism of calcium carbonate particles synthesized by the CO 2 bubbling method has been investigated. Samples were sequentially taken during the bubbling process to be structurally evaluated by X-ray diffraction and scanning electron microscopy. As a result, it has been elucidated that there are three development stages (A, B, and C) in the formation of the hollow structure. In stage A, amorphous CaCO 3 precipitates as primary particles with the decreasing pH by CO 2 bubbling. The primary particles then aggregate around pH 9.1 to form secondary particles, and turbidity ensues. Furthermore, because of the decreasing pH, the primary particles on the surface of the secondary particles begin to transform into the vaterite phase and form a shell. During stage B, the surface potential decreases along with a steep decrease in the pH, interparticle attraction of the primary particles on the surface of the secondary particles becomes stronger, and a highly compacted shell is formed. At the same time as vaterite precipitation on the surface, dissolution of the amorphous phase on the inside rapidly proceeds to precipitate vaterite particles by adhesion to the inside of the outer shell. At this time, contraction due to the release of water occurs and the hollow structure is formed. Moreover, it has been elucidated that, at pH ≤7, redissolution of the particulates inside the secondary particles occurs and definite shell structures are formed.

Split-ring resonators (SRRs) are attractive owing to the interaction with a magnetic field of incident light. Here, we report the fabrication of uniform arrays of about 360 million Au SRRs with a line width of approximately 50 nm by reactive-monolayer-assisted thermal nanoimprint lithography over a 5-mm square area. Furthermore, we present an experimental demonstration of the oscillation of free electrons excited by a magnetic field at 690 nm in the visible frequency region. The fabrication and optical investigation of SRR arrays over such large areas will facilitate opportunities to realize advanced optical devices.

Dewetting behaviors of sub-50-nm-thick ultraviolet-curable resin films comprising hydroxy-containing (meth)acrylate monomers on modified Au-plated substrates were investigated by fluorescence microscopy. Hydroxy-terminated alkanethiol-adsorbed monolayers on Au surfaces suppressed dewetting of the thin spin-coated films and allowed the fabrication of 50-nm-line-width Au split-ring resonator (SRR) arrays by ultraviolet nanoimprint lithography.

No abstract