Rensselaer Polytechnic Institute

About: Rensselaer Polytechnic Institute is a education organization based out in Troy, New York, United States. It is known for research contribution in the topics: Terahertz radiation & Finite element method. The organization has 19024 authors who have published 39922 publications receiving 1414699 citations. The organization is also known as: RPI & Rensselaer Institute.

Abundance and Isotopic Composition of Gases in the Martian Atmosphere from the Curiosity Rover

Abstract: Volume mixing and isotope ratios secured with repeated atmospheric measurements taken with the Sample Analysis at Mars instrument suite on the Curiosity rover are: carbon dioxide (CO2), 0.960(±0.007); argon-40 (40Ar), 0.0193(±0.0001); nitrogen (N2), 0.0189(±0.0003); oxygen, 1.45(±0.09) × 10−3; carbon monoxide, < 1.0 × 10−3; and 40Ar/36Ar, 1.9(±0.3) × 103. The 40Ar/N2 ratio is 1.7 times greater and the 40Ar/36Ar ratio 1.6 times lower than values reported by the Viking Lander mass spectrometer in 1976, whereas other values are generally consistent with Viking and remote sensing observations. The 40Ar/36Ar ratio is consistent with martian meteoritic values, which provides additional strong support for a martian origin of these rocks. The isotopic signature δ13C from CO2 of ~45 per mil is independently measured with two instruments. This heavy isotope enrichment in carbon supports the hypothesis of substantial atmospheric loss.

Plasma wave detection of terahertz radiation by silicon field effects transistors: Responsivity and noise equivalent power

Abstract: Si metal oxide semiconductor field effect transistors (MOSFETs) with the gate lengths of 120–300nm have been studied as room temperature plasma wave detectors of 0.7THz electromagnetic radiation. In agreement with the plasma wave detection theory, the response was found to depend on the gate length and the gate bias. The obtained values of responsivity (⩽200V∕W) and noise equivalent power (⩾10−10W∕Hz0.5) demonstrate the potential of Si MOSFETs as sensitive detectors of terahertz radiation.

Silicon oxycarbide glasses: Part II. Structure and properties

Abstract: Silicon oxycarbide glass is formed by the pyrolysis of silicone resins and contains only silicon, oxygen, and carbon. The glass remains amorphous in x-ray diffraction to 1400 °C and shows no features in transmission electron micrographs (TEM) after heating to this temperature. After heating at higher temperature (1500–1650 °C) silicon carbide lines develop in x-ray diffraction, and fine crystalline regions of silicon carbide and graphite are found in TEM and electron diffraction. XPS shows that silicon-oxygen bonds in the glass are similar to those in amorphous and crystalline silicates; some silicons are bonded to both oxygen and carbon. Carbon is bonded to either silicon or carbon; there are no carbon-oxygen bonds in the glass. Infrared spectra are consistent with these conclusions and show silicon-oxygen and silicon-carbon vibrations, but none from carbon-oxygen bonds. 29Si-NMR shows evidence for four different bonding groups around silicon. The silicon oxycarbide structure deduced from these results is a random network of silicon-oxygen tetrahedra, with some silicons bonded to one or two carbons substituted for oxygen; these carbons are in turn tetrahedrally bonded to other silicon atoms. There are very small regions of carbon-carbon bonds only, which are not bonded in the network. This “free” carbon colors the glass black. When the glass is heated above 1400 °C this network composite rearranges in tiny regions to graphite and silicon carbide crystals. The density, coefficient of thermal expansion, hardness, elastic modulus, index of refraction, and viscosity of the silicon oxycarbide glasses are all somewhat higher than these properties in vitreous silica, probably because the silicon-carbide bonds in the network of the oxycarbide lead to a tighter, more closely packed structure. The oxycarbide glass is highly stable to temperatures up to 1600 °C and higher, because oxygen and water diffuse slowly in it.