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Showing 1 to 20 of 121 for “"77 K"”.
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Synthesis, structure and spectroscopic investigations of luminescent heterobimetallic gold(I)-Rhodium(I) species
… of glass-solution and solid state samples at 77 K are reported for 2-5 and interpreted in context of crystallographic structure, electronic structure, and time-dependent density functional theory (TD-DFT) calculations. 2-5 are intensely luminescent at 77 K, with 4 and 5 exhibiting "dual …
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A new approach to the study of surface phenomena, measurements of diffusion rates, intermolecular distances and electronic properties of CO chemisorbed on supported platinum catalysts by nuclear magnetic resonance
… that a measurement of transverse relaxation at 77 K can be used to measure relative distances among molecules in the adsorbed layer. His measurements of transverse relaxation and of spin-lattice relaxation are consistent with the geometry of CO layers chemisorbed on single crystal surfaces. He …
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13C-nuclear-magnetic-resonance of carbon monoxide on platinum: Study of a highly dispersed catalyst
… Korringa relation, T1T(AH/H)2 = constant. From 77 K to 300 K, the relaxation of the omagnetization is multiexponential: the distribution in T1's reflects a distribution in Knight shifts arising from a distribution of CO chemisorption sites at the Pt surface. Above 300 K, the relaxation is …
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Radiation-induced mobility degradation in DMOS transistors.
… performed at room temperature and at 77 K to analyze mobility degradation due to the same density of radiation-induced defects at these two different temperatures. Radiation-induced mobility degradation is more pronounced at 77 K than at room temperature, due to increased relative …
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Acoustic Phonon Scattering in Modulation Doped Aluminum(x) Gallium(1-X) Arsenide/gallium Arsenide Heterojunctions
… reported measurements of the mobility at 77 K we determine an upper limit for the deformation potential constant of 11 eV.
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Carbon-13 - Nuclear - Magnetic - Resonance of Carbon Monoxide on Platinum: Study of a Highly Dispersed Catalyst (Nmr)
… T(,1)T((DELTA)H/H(,0))('2) = constant. From 77 K to 300 K, the relaxation of the magnetization is multiexponential: the distribution in T(,1)'s reflects a distribution in Knight shifts arising from a distribution of CO chemisorption sites at the Pt surface. Above 300 K, the relaxation is …
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NMR studies of acetylene absorbed on supported platinum catalysts
… supported platinum catalysts. Measurements from 77""K to 158°K of the spin-lattice relaxation behavior of carbon-13 reveal multiple-exponential behavior. Calculations rule out an anisotropic T 1 as an explanation for the multiple-exponential behavior. Carbon-proton SEDOR measurements indicate …
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Electrical characterization of high temperature superconductors as a function of temperature
… 2223/Ag) tapes at temperatures ranging from 77 K to 110 K were measured using a typical four-terminal technique for two different BSCCO-2223/Ag tapes manufactured by Vacuumschmelze (VAC). The critical currents for the two VAC samples were measured as a function of magnetic field strength. The …
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Cryogenic deformation of two comet and asteroid analogs under varying conditions of saturation
… of cryogenic temperatures (295 K down to 77 K) and light confining pressures (1 to 5 MPa). The compressive strength of both materials was determined under varied conditions of saturation, from oven-dried (~0% water content) to fully saturated, and both brittle and ductile behavior was …
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Photoluminescent properties of vacuum deposited cadmium sulfide films
… o The green luminescence in the films at 77 K wa.s similar to the emission reported for donor-doped CdS. Donor-doped CdS emission differ8~: from the phonon-assisted ""edge emission"" starting at 5140 ~ observed in pure CdS in that the emission peak at 5230 ~, corresponding to emission of …
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Indium-Gallium - Phosphide-Arsenide Quantum-Well Heterostructure Lasers Grown on Gallium-Arsenide Substrate by Liquid Phase Epitaxy (Miscibility)
… room temperature (cw, 300 K) at a wavelength of 7700 (ANGSTROM), but with a limited operating life, as described. The shortest wavelength obtained in this study is 6600 (ANGSTROM) at 77 K. This is achieved by bandfilling of a quantum-well sample having a well thickness of (TURN) 200 (ANGSTROM). …
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Long-wavelength gallium-indium-arsenide quantum wire lasers
… of the simple surface diffusion model. The 77 K threshold current densities (J$\sb{\rm th}$) for $\rm Ga\sb{x}In\sb{1-x}As$ MQWR laser diodes with laser cavities along the (110) and (110) directions showed an anisotropy ratio of $\sim$10. Due to the directionality of two-dimensional quantum …
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Synthesis and Characterization of Nanoporous Copolymers with Potential Gas Storage Applications
… using nitrogen sorption/desorption isotherms at 77 K and molecular simulations. These alternating copolymers were found to have Brunauer-Emmett-Teller (BET) surface areas in the range of 20-40 m2/g. Surface areas of these alternating copolymers increased as the steric crowding of the polymer …
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The Photochemistry of 3- and 4-Nitro Phenyl Azides
… at room temperature or in a frozen glass at 77 K gives triplet nitrenes. The products of the reaction of triplet nitrenes depend on the power of the light source. Triplet 4-nitrophenyl nitrene dimerizes to form azobenzene at a diffusion controlled rate and reacts with the tertiary amine by …
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Optical absorption of bismuth silicon oxide (Bi₁₂SiO₂₀) crystals
… taken in the range of 0.4 - 11 pm at 300 K and 77 K using a spectrometer. The results show that near the band edge, there is evidence of indirect transitions at 2.3 eV and excition transitions at 1.8 eV. Low temperature measurements revealed peaks of free carrier absorption in the visible light …
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Polymers from the natural product betulin : a microstructural investigation
… of porous substances like nitrogen sorption at 77 K do not seem to be sufficient to answer all arising questions about the microstructure of such materials. In this thesis, microporous polymers from an abundant natural resource, betulin, will be presented. Betulin is a large-scale byproduct of …
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