Isotropic contractive scaling of laser written microstructures in vitrified aerogels

A novel route is presented enabling minimization of feature sizes via laser ablative micro-patterning in highly porous silica aerogel monoliths and subsequent viscous sintering. Vitrification yields isotropically contracted silica solids preserving their original stereometric forms. The contraction depends on aerogel structure and porosity and we demonstrate here the first realization of a 3:1 ratio. Surface relief and void micropatterns inscribed in the monolith also undergo isotropic contraction and feature minimization beyond the spatial resolution of their original recording. Experimental results provide clear evidence that embedded void structures undergo contraction larger than the nominal stereometric scaling. This is a demonstration of a generic principle that enables fundamental physical resolution limits to be surpassed, leading to new avenues in micro- and nano-fabrication technologies

Data for Isotropic contractive scaling of laser written microstructures in vitrified aerogels

A novel route is presented enabling minimization of feature sizes via laser ablative micro-patterning in highly porous silica aerogel monoliths and subsequent viscous sintering. Vitrification yields isotropically contracted silica solids preserving their original stereometric forms. The contraction depends on aerogel structure and porosity and we demonstrate here the first realization of a 3:1 ratio. Surface relief and void micropatterns inscribed in the monolith also undergo isotropic contraction and feature minimization beyond the spatial resolution of their original recording. Experimental results provide clear evidence that embedded void structures undergo contraction larger than the nominal stereometric scaling. This is a demonstration of a generic principle that enables fundamental physical resolution limits to be surpassed, leading to new avenues in micro- and nano-fabrication technologies.</span

A Study of Quantum Confinement Effects in Ultrathin NiO Films Performed by Experiment and Theory

Ultrathin NiO films in the thickness range between 1 and 27 nm have been deposited on high-quality quartz substrates by direct magnetron sputtering under a rough vacuum with a base pressure of 2 &times; 10&minus;2 mbar. The sputtering target was metallic Ni; however, due to the rough vacuum a precursor material was grown in which most of Ni was already oxidized. Subsequent short annealing at temperatures of about 600 &deg;C in a furnace in air resulted in NiO with high crystallinity quality, as atomic force microscopy revealed. The images of surface morphology showed that the NiO films were continuous and follow a normal grain growth mode. UV-Vis light absorption spectroscopy experiments have revealed a blue shift of the direct band gap of NiO. The band gap was determined either by Tauc plots (onset) or by the derivative method (highest rate of absorbance increase just after the onset). The experimental results are interpreted as evidences of quantum confinement effects. Theoretical calculations based on Hartree Fock approximation as applied for an electron-hole system, in the framework of effective mass approximation were carried out. The agreement between theory and experiment supports the quantum confinement interpretation