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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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Atoms, molecules, and atomic and molecular ions generated by solar wind interactions with dust grains of the zodiacal cloud are discussed. The main processes leading to the generation of these particles are described and relevant methods of observation are examined.
Polarization of Lyman alpha radiation emitted in electron collisions with hydrogen atoms and molecules
Experimental determination of the paired interaction potential of atoms and molecules composing the atmospheres of the earth and the planets is described.
Sudden approximation applied to computation of rotational transition probability and inelastic total cross sections for scattering of polar and nonpolar diatomic molecules by atoms
Approximation method using sum rules for energy shift in atomic system due to interaction of electrons with vacuum electromagnetic field applied to hydrogen, helium and lithium atom ground states and hydrogen molecule
A literature review on the present state of knowledge in photoionization is presented. Various experimental techniques that have been developed to study photoionization, such as fluorescence and photoelectron spectroscopy, mass spectroscopy, are examined. Various atoms and molecules were chosen to illustrate these techniques, specifically helium and xenon atoms and hydrogen molecules. Specialized photoionization such as in positive and negative ions, excited states, and free radicals is also treated. Absorption cross sections and ionization potentials are also discussed.
Residual gas analyzer and leak detector by time of flight measurements on neutral metastable atoms and molecules between pulsed electron gun and auger surface detector
The directions and energy distributions of neutral atoms and molecules ejected from Io are modeled analytically. The particles are emitted from the Io exosphere by collisions of incident plasma ions. Some of the Io atmosphere is attributed to particles sputtered off the surface by incoming plasma ions, while other departing particles originate at the top of volcanic plumes. Account is taken of the thermal motion of incident plasma and Io's gravitational field when calculating the distribution of the ejected particles. The distributions associated with each type of ejection force are projected to be different and highly dependent on the inclusion of realistic cross-sections. Attention is focused on Na-rich species and defining ejection processes which can be verified with ground-based observations. It is, however, concluded that no particles are ejected directly from the surface by Jean's escape.
Computer program to predict spectra from electronic transitions of diatomic molecules and atoms, noting line intensity distribution by Voigt profile
Computer program predicts the spectra resulting from electronic transitions of diatomic molecules and atoms in local thermodynamic equilibrium. The program produces a spectrum by accounting for the contribution of each rotational and atomic line considered.
Oxidation of semiconductors and high-temperature superconductors achieved at lower temperatures by use of oxygen molecules or atoms raised into specific excited states. Use of excited oxygen (or other species) of interest in research on kinetics and mechanisms of chemical reactions. Used in ultra-high-vacuum chamber also equipped for such surface-analytical techniques as x-ray photoelectron spectroscopy.
Computer program for line-by-line calculation of spectra from diatomic molecules and atoms assuming Voigt line profile
Sudden approximation applied to rotational transition probabilities and inelastic total cross sections for scattering of homonuclear diatomic molecules by atoms
The C10H8(+) cation and its dehydrogenated derivatives, C10H7(+) and C10H6(+), have been studied using a selected ion flow tube (SIFT). Reactions with molecules and atoms of interstellar interest show that C10H8(+) reacts with N md O to give neutral products HCN and CO, respectively. C10H6(+) and C10H6(+) are moderately reactive and reactions proceed through association with molecules. The implications of these results for the depletion of C10H(n)(+) in the interstellar medium are briefly discussed.
Diatomic polar molecule rotational excitation by atomic impact to obtain transition cross section angular distribution and energy dependence
Rotational and vibrational transitions in a diatomic molecule caused by collisions with an atom are analyzed by a semiclassical method for conditions where the rotational transitions can be handled well by the sudden approximation and the vibrational transitions belong to the adiabatic regime. The contribution to the vibrational transition probability from the correction, which takes the finite value of the spacing between rotational energy levels into account, is examined.-
Preliminary results of a research program to determine energy partitioning in spacecraft thermal protection materials due to atom recombination at the gas-surface interface are presented. The primary focus of the research is to understand the catalytic processes which determine heat loading on Shuttle, Aeroassisted OTV, and NASP thermal protection surfaces in nonequilibrium flight regimes. Highly sensitive laser diagnostics based on laser-induced fluorescence and resonantly-enhanced multiphoton ionization spectroscopy are used to detect atoms and metastable molecules. At low temperatures, a discharge flow reactor is employed to measure deactivation/recombination coefficients for O-atoms, N-atoms, and O2. Detection methods are presented for measuring O-atoms, O2 and N2, and results for deactivation of O2 and O-atoms on reaction-cured glass and Ni surfaces. Both atom recombination and metastable product formation are examined. Radio-frequency discharges are used to produce highly dissociated beams of atomic species at energies characteristic of the surface temperature. Auger electron spectroscopy is employed as a diagnostic of surface composition in order to accurately define and control measurement conditions.
Charge exchange followed by radiative stabilization are the main processes responsible for the recent observations of X-ray emission from comets in their approach to the Sun. A new apparatus was constructed to measure, in collisions of HCIs with atoms and molecules, (a) absolute cross sections for single and multiple charge exchange, and (b) normalized X-ray emission cross sections.