No abstract

We report a general chemical strategy for producing reduced-symmetry metallodielectric nanoparticles, nanocups, and nanocaps that combines nanoscale masking techniques and nanoparticle-seeded electroless plating. Using this approach, silica nanoparticles with a gold cup-shaped shell and, alternatively, a gold cap, are obtained. The plasmon response of both nanostructures is a sensitive function of orientation of the nanostructure with respect to the direction and polarization of incident light. This orientation dependence is examined experimentally by studying the extinction spectra of oriented nanocups and nanocaps on transparent substrates, and is also evaluated theoretically using a three-dimensional finite difference time domain (FDTD) method. † Part of the special issue "Arnim Henglein Festschrift".

Frequency upconversion of Er3+ in alkali bismuth gallate glasses have been investigated. The upconversion mechanisms are discussed, and the dominant mechanisms are excited state absorption for the H11/22→I15/24 and S3/24→I15/24 transitions, and energy transfer upconversion for the F9/24→I15/24 transition. Intense green (around 525–550 nm) and red (around 660 nm) emission bands were observed under 800 nm excitation. At a pump intensity of 15.6 W/cm2, frequency upconversion efficiencies of 2.1×10−2 and 4.8×10−3 were obtained for the green and red emissions, respectively. The results are the highest among doped oxide glasses, and are comparable to those reported for Er3+/Yb3+ codoped fluoride glasses.

No abstract