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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1966

Electron beam diagnostics.

Spectroscopic electron beam diagnostic technique, examining negligible effect elevated vibrational temperatures have on measured rotational temperatures of molecular nitrogen

ELECTRON BEAM↗
NASA NTRS2007

Modeling Carbon and Hydrocarbon Molecular Structures in EZTB

A software module that models the electronic and mechanical aspects of hydrocarbon molecules and carbon molecular structures on the basis of first principles has been written for incorporation into, and execution within, the Easy (Modular) Tight-Binding (EZTB) software infrastructure, which is summarized briefly in the immediately preceding article. Of particular interest, this module can model carbon crystals and nanotubes characterized by various coordinates and containing defects, without need to adjust parameters of the physical model. The module has been used to study the changes in electronic properties of carbon nanotubes, caused by bending of the nanotubes, for potential utility as the basis of a nonvolatile, electriccharge- free memory devices. For example, in one application of the module, it was found that an initially 50-nmlong carbon, (10,10)-chirality nanotube, which is a metallic conductor when straight, becomes a semiconductor with an energy gap of .3 meV when bent to a lateral displacement of 4 nm at the middle.

Lee, Seungwon↗
NASA NTRS1991

Origin of amphiphilic molecules and their role in primary structure formation

Attempts to solve two fundamental questions are described: the first concerns which mechanisms were responsible for the self-assembly of membrane structures on the prebiotic Earth, and the second concerns the routes by which considerable amounts of membrane amphiphiles formed from simpler hydrocarbons. The physicochemical properties of several amphiphilic compounds extracted from the Murchison carbonaceous chondrite were studied, using infra-red and fluorescent spectroscopy, measurements of surface activity, chromato-mass spectrometry, and polarization and electron microscopy. The results supported previous observations that amphiphilic and aromatic hydrocarbons were present in significant quantities, and the first demonstration of surface activity among a number of acidic derivatives of hydrocarbons is reported. In addition, one fraction of the surface-active compounds can form bilayer structures, showing that membranes could have self-assembled on the prebiotic Earth. Photochemical oxidation of hydrocarbons is shown to be a likely source of the amphiphilic molecules required for the self-assembly of primary membrane structures.

NASA Discipline Number 52-20↗
NASA NTRS1975

Auroral N2 vibrational excitation and the electron density trough

Through various processes molecular nitrogen within the nocturnal auroral oval is vibrationally excited, substantially increasing the rate at which O(+) is lost via the reaction O(+) + N2* yields NO(+) + N. Owing to the action of thermospheric winds and diffusion, N2* does not remain at its point of origin but is transported to regions outside the auroral oval where it can act to substantially reduce the F-region electron density. For an equatorward transport speed of 100 m/sec, N2* can travel 3 to 4 deg of latitude before quenching with atomic oxygen substantially reduces the N2* density. This process may contribute significantly to the formation of the midlatitude F-region electron density trough.

Schunk, R. W.↗
NASA NTRS1975

Heat detection and compositions and devices therefor

Temperature change of a substrate such as a microelectronic component is sensed and detected by means of a mixture of a weak molecular complex of an electron donor compound such as an organic amine and an electron acceptor compound such as nitroaromatic compound. The mixture is encapsulated in a clear binder such as a vinyl resin.

Rembaum, A.↗
NASA NTRS1977

Theory of inelastic ion-atom scattering at low and intermediate energies

Ab initio calculations are presented of inelastic energy loss and ionization phenomena associated with Ar(+)-Ar collisions at small distances of closest approach and for laboratory collision energies ranging from several keV to several hundred keV. Outer-shell excitations are handled statistically; inner-shell excitations are calculated from the viewpoint of quasidiabatic molecular orbital promotion. Auger electron yield, average state of ionization, and average inelastic energy loss are calculated per collision as a function of distance of closest approach of the collision partners for several laboratory collision energies. Average charge-state probabilities per collision partner are calculated as a function of the average inelastic energy loss per atom. It is shown that the structure in the data is due to the underlying structure in the inner-shell independent-electron quasimolecular promotion probabilities.

Schmid, G. B.↗
NASA NTRS1978

Radiation energy conversion in space; Conference, 3rd, NASA Ames Research Center, Moffett Field, Calif., January 26-28, 1978, Technical Papers

Concepts for space-based conversion of space radiation energy into useful energy for man's needs are developed and supported by studies of costs, material and size requirements, efficiency, and available technology. Besides the more studied solar power satellite system using microwave transmission, a number of alternative space energy concepts are considered. Topics covered include orbiting mirrors for terrestrial energy supply, energy conversion at a lunar polar site, ultralightweight structures for space power, radiatively sustained cesium plasmas for solar electric conversion, solar pumped CW CO2 laser, superelastic laser energy conversion, laser-enhanced dynamics in molecular rate processes, and electron beams in space for energy storage.

Billman, K. W.↗
NASA NTRS1981

Mean excitation energy for molecules of hydrogen and carbon

The Gordon-Kim electron gas model of molecular bonding is used to calculate correction factors for the Bragg rule for molecules of hydrogen and carbon. General rules for molecular mean excitation energies are obtained that agree to about 4% with experimental values.

Wilson, J. W.↗