title: Plasmonic Control and Stabilization of Asymmetric Light Scattering from Ag Nanocubes on TiO2.
abstract: When plasmonic nanoparticles are placed on a highly refractive semiconductor substrate, we can expect three different effects: (i) resonance mode splitting, (ii) asymmetric light scattering based on the split modes, and (iii) site-selective nanoetching due to plasmon-induced charge separation (PICS) at the nanoparticle-semiconductor interface. Here, we develop novel photofunctional materials by taking advantage of those three effects. More specifically, we control the asymmetric scattering of Ag nanocubes on TiO2by PICS, so as to develop materials for photodrawing of one-way visible translucent images and multicolor scattering images. The one-way visible translucent images, which are translucent scattering images visible only from the back side, are drawn by anaerobic bottom-selective etching of the Ag nanocubes. For drawing the multicolor scattering images, a scattering color of Ag nanocubes is changed from yellow to green by the anaerobic bottom-selective etching and from yellow to red by aerobic nonselective etching. We also theoretically and experimentally examined the contribution of a possible thermal effect to the nanoetching, and revealed that the contribution is negligible; Ag nanocubes on TiO2are stable even at 473 K for 2 h in the dark, whereas the theoretically expected temperature increase under light is less than 1 K. In addition, we developed methods to stabilize the Ag nanocubes by inactivating PICS. When Ag nanocubes on TiO2are coated with a thin polymer layer, PICS is decelerated and the stability is improved. Replacing TiO2with diamond, which does not accept electrons from plasmonic nanoparticles, is also an effective method to stabilize the nanocubes.
authors.affiliation: Institute of Industrial Science, The University of Tokyo , 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Saito
authors.affiliation: Division of Frontier Materials Science and Center for Promotion of Advanced Interdisciplinary Research, Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Setoura
authors.affiliation: Division of Frontier Materials Science and Center for Promotion of Advanced Interdisciplinary Research, Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan.
authors.forename: Syoji
authors.initials: S
authors.lastname: Ito
authors.affiliation: Division of Frontier Materials Science and Center for Promotion of Advanced Interdisciplinary Research, Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyasaka
authors.affiliation: Institute of Industrial Science, The University of Tokyo , 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Mitsuda
authors.affiliation: Institute of Industrial Science, The University of Tokyo , 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
authors.forename: Tetsu
authors.identifier: http://orcid.org/0000-0001-8738-9837
authors.initials: T
authors.lastname: Tatsuma
keywords: Ag nanocube; asymmetric light scattering; multicolor scattering; plasmon-induced charge separation; site-selective nanoetching