We present field deployment results of a portable optical absorption spectrometer for localization and quantification of fugitive methane (CH) emissions. Our near-infrared sensor targets the 2ν R(4) CH transition at 6057.1 cm (1651 nm) via line-scanned tunable diode-laser absorption spectroscopy (TDLAS), with Allan deviation analysis yielding a normalized 2.
View Article and Find Full Text PDFResults from three years of continuous monitoring of environmental conditions using a wireless sensor platform installed at The Cloisters, the medieval branch of the New York Metropolitan Museum of Art, are presented. The platform comprises more than 200 sensors that were distributed in five galleries to assess temperature and air flow and to quantify microclimate changes using physics-based and statistical models. The wireless sensor network data shows a very stable environment within the galleries, while the dense monitoring enables localized monitoring of subtle changes in air quality trends and impact of visitors on the microclimate conditions.
View Article and Find Full Text PDFWe present characterization results of microscopic platinum wires as bolometers. The wire lengths range from 16 μm down to 300 nm. Thus they are in many cases significantly smaller in size than the wavelength of the radiation from the 1200 K blackbody source they were exposed to.
View Article and Find Full Text PDFThe polarization of the thermal radiation emitted from individual nanoheaters is investigated for nanoheaters with widths ranging from 500 nm to 2000 nm. The polarization is oriented along the long axis of the nanoheater for widths below 600 nm and rotates by 90 degrees and becomes perpendicular for widths above 900 nm. For certain width nanoheaters the orientation of the polarization of the thermal emission can be rotated from parallel to perpendicular by changing the temperature of the nanoheater.
View Article and Find Full Text PDFHere we report polarization-sensitive, thermal radiation measurements of individual, antenna-like, thin film Platinum nanoheaters. These heaters confine the lateral extent of the heated area to dimensions smaller (or comparable) to the thermal emission wavelengths. For very narrow heater structures the polarization of the thermal radiation shows a very high extinction ratio as well as a dipolar-like angular radiation pattern.
View Article and Find Full Text PDFStrain plays a critical role in the properties of materials. In silicon and silicon-germanium, strain provides a mechanism for control of both carrier mobility and band offsets. In materials integration, strain is typically tuned through the use of dislocations and elemental composition.
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