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NMR Used for Environmental Restoration Researchers at Pacific Northwest Laboratory are using a suite of nuclear magnetic resonance (NMR) spectrometers to research molecular problems related to environmental restoration. NMR is being used to examine catalytic conversion of environmental toxins to study the physical integrity of materials used for waste storage. Researchers are using NMR to determine how carbon tetrachloride is destroyed when it is converted to methane catalysts that can destroy a wider range of contaminants. Paul Ellis, head of the Department of Energy's Environmental Molecular Sciences Laboratory (EMSL) conducting the research at Pacific Northwest Laboratory, said that more research is needed to test the applicability of the methods. According to the scientists, EMSL catalysis research would have applications wherever toxic materials are used, including energy, petrochemical, fuel and plastics production or manufacturing sites.

Vertical-Cavity Surface Emitting InGaAs Laser Yields High Efficiency A team of researchers led by Kent Choquette, Kevin Lear, and Richard Schneider in Sandia National Laboratories' Center for Compound Semiconductor Technology demonstrated a 53% electrical-to-optical power conversion efficiency from an indium-galliumarsenide vertical-cavity surface emitting laser (VCSEL) operating at 980 nm. In contrast to the conventional semiconductor laser that emits light from the edge of a cleaved wafer, a VCSEL emits light perpendicular to the wafer surface, rendering it easy to fashion into densely packed arrays of lasers on a single chip. The researchers used a series of advances in the design and growth of the multilayered device heterostructures, combined with a "selective oxidation" fabrication technology to realize the low electrical resistance and high optical and electrical confinement needed to achieve the high efficiency.

NEW CVD Gases High Purity Methylsilane

VCSELs are fabricated by sequentially layering atoms of semiconductor materials on a substrate. The center layer is the light-emitting optical cavity, and the surrounding layers are mirrors. Electrical charges approaching from the mirror layers above and below get trapped and recombine in the cavity to emit light. The mirrors reflect the emitted light, which is amplified in the central layer, to produce the laser beam. The selective oxidation approach involved embedding specially designed layers of aluminum-gallium-arsenide in the VCSEL structure during the growth process. This is followed by the formation of mesas by dry etching. The layers were oxidized to form an aluminum oxide aperture that defined the current injection path for the VCSEL device as well as providing an enhancement to the optical confinement of photons in the device. The collective effects of the low electrical resistance combined with the oxide aperture resulted in the high operating efficiency of the devices.

Other VOLTAIX Products: (Applications) Germane, Digermane

First reported as a precursor for heteroepitaxial silicon (a-Si, heteroepi-Si)