The morphology, structural and optical properties of void-assisted freestanding HVPE-AlN films were investigated by a combination of non-destructive microscopic and spectroscopic techniques. The freestanding approximately 80 mm thick clear film has a wurtzite crystalline structure with remarkable properties around the central film region. The E2(high)-phonon frequency coincides with reported st...

Laterally large (≈3 µm), atomically thin 2D Bi2O2CO3 nanosheets (2D bismuth oxycarbonate, bismutite) are fabricated via sonochemically assisted, template-free synthesis. Keys to the synthesis of freestanding, laterally from bulk Bi powder choice suspension medium, controlled reaction temperatures, and several hours processing time. Lateral sizes can be between µm-sized tens nm sized nanoflakes ...

Dye-sensitized solar cells (DSSCs) were fabricated with closed- or open-ended freestanding TiO₂ nanotube arrays as photoelectrodes that were decorated with carbon materials and large TiO₂ nanoparticles (NPs) to enhance energy conversion efficiency. The energy conversion efficiency of DSSCs based on open-ended freestanding TiO₂ nanotube arrays increased from 4.47% to 5.39%, compared to the DSSCs...

For sensors constructed by freestanding membranes, when the gap between a freestanding membrane and the substrate or between membranes is at micron scale, the effects of near-field radiative heat transfer on the sensors' thermal performance should be considered during sensor design. The radiative heat flux is transferred from a membrane to a plane or from a membrane to a membrane. In the curren...

OBJECTIVE To assess long term compliance with the California Smoke-Free Workplace Law in Los Angeles County freestanding bars and bar/restaurants. DESIGN Population based annual site inspection survey of a random sample of Los Angeles County freestanding bars and bar/restaurants was conducted from 1998 to 2002. MAIN OUTCOME MEASURES The primary outcomes of interest were patron and employee ...

We report a comprehensive study of the two-phonon intervalley (2D) Raman mode in graphene monolayers, motivated by recent reports of asymmetric 2D-mode line shapes in freestanding graphene. For photon energies in the range 1.53-2.71 eV, the 2D-mode Raman response of freestanding samples appears as bimodal, in stark contrast with the Lorentzian approximation that is commonly used for supported m...