Experimental demonstration of graphene plasmons working close to the near-infrared window

Due to strong mode-confinement, long propagation-distance, and unique tunability, graphene plasmons have been widely explored in the mid-infrared and terahertz windows. However, it remains a big challenge to push graphene plasmons to shorter wavelengths in order to integrate graphene plasmon concepts with existing mature technologies in the near-infrared region. We investigate localized graphene plasmons supported by graphene nanodisks and experimentally demonstrated graphene plasmon working at 2 {\mu}m with the aid of a fully scalable block copolymer self-assembly method. Our results show a promising way to promote graphene plasmons for both fundamental studies and potential applications in the near-infrared window.Comment: 6 pages, 4 figures, a revised versio

Stabilization of metastable tetragonal zirconia nanocrystallites by surface modification

Metastable tetragonal zirconia nanocrystallites were studied in humid air and in water at room temperature (RT). A stabilizing effect of different surfactants on the tetragonal phase was observed. Furthermore, the phase stability of silanized metastable tetragonal zirconia nanocrystallites was tested by prolonged boiling in water. The samples were analyzed with X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Changes in the monoclinic volume fraction in the samples were calculated. A number of surfactants were screened for their ability to stabilize the tetragonal phase upon exposure to humidity. Only silanes and phosphate esters of these were able to stabilize the tetragonal phase in water. Even as small amounts of silanes as 0.25 silane molecule per nm2 are able to stabilize the tetragonal phase in water at RT. Aminopropyl trimethoxy silane and γ-methacryloxypropyl trimethoxy silane were even capable of preventing phase transformation during boiling for 48 h in water

Diffusion rate of hydrogen peroxide through water-swelled polyurethane membranes

In our efforts to design an optical sensor for hydrogen peroxide, we have realized the importance of knowing/controlling the diffusion of hydrogen peroxide to the indicator, especially in the case of an irreversible indicator. Since we found little literature data, we decided to test the permeability of hydrogen peroxide in commercially available polymers, focusing on the polyurethanes HydroMed™ and HydroThane™, which are commonly used for immobilization matrices in optical sensors. Measured values are between 5.12 10−9 ± 8.50 10−10 and 2.25 10−6 ± 1.00 10−7 cm2 s−1. Keywords: Hydrogen peroxide, Polymer membrane, Permeability, Diffusivit