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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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Potential of photodissociative laser system for converting solar radiation to monochromatic coherent emission
Photodissociation of hydrogen molecules in H I regions of interstellar medium, evaluating lifetime and density
The Martian atmosphere has many features in common with the terrestrial mesosphere. Both share similar pressure and temperature ranges, and much of the same chemistry operates in each. For example, the radical species H, OH, and H(sub 2)O, which comprise the odd hydrogen family, are of central importance in the catalytic destruction of CO and O(sub 3) in both atmospheres. The inclusion of recent chemical kinetics data, specifically temperature dependent CO(sub 2) absorption cross-sections, into our one dimensional photochemical model of the Martial atmosphere shows that oxidation of CO by odd hydrogen is too efficient. The incorporation of smaller cross sections for CO(sub 2) leads to an enhanced photolysis rate of water vapor, increasing odd hydrogen to the point where the predicted mixing ratio of CO in our model is substantially less than the observed value of 6.5 x 10(sup -4). Interestingly, most photochemical models of the terrestrial mesosphere underestimate the CO and O(sub 3) densities using currently accepted photodissociation and kinetic rate coefficients. This has also been attributed to an overabundance of odd hydrogen in the models. We shall show that agreement between models and observations of CO in the Martian atmosphere as well as of CO and O(sub 3) in the terrestrial mesosphere can be achieved by revising the rate constants for the reactions OH + HO(sub 2) and CO + OH within their published uncertainties. The fact that similar revisions alleviate discrepancies in both the terrestrial and Martian atmospheres warrants a re-evaluation of these key rate constants at the appropriate temperatures and pressures.
Origin of diatomic carbon Swan bands in cometary emissions due to hydrocarbon photodissociation
Dayglow green line and possible excitation mechanisms such as photodissociation and dissociative recombination of oxygen
Mariner IV models of three Mars atmospheric layers analogous to terrestrial E, F-1 and F-2 layers, considering relative mass densities, temperatures, carbon dioxide photodissociation and ionization profile
Photochemical production of cometary molecular radicals and ions, comparing observed densities with calculations based on photodissociation and photoionization
Recombination mechanism between CO and O produced by photodissociation of carbon dioxide in upper atmosphere of Venus and Mars
Spaceborne planetary UV spectroscopic search for atoms and molecules basic to life, specifically molecular N and water vapor photodissociation products
Positively charged diatomic hydrogen molecules interstellar extinction and photodissociation cross section in terms of formation mechanisms
Atmospheric water vapor photodissociation and resulting O evolution recalculated for determining O abundance in absence of biological activity
Nimbus 3 satellite observations of near UV solar flux intensity and variability, describing instrumentation and measurement of radiation producing molecular oxygen photodissociation
Earth atmosphere formation and oxygen-carbon dioxide balance mechanisms, including water vapor photodissociation, photosynthesis, fossil fuel burning, etc
Vacuum ultraviolet photoionization and photodissociation of associated and polymeric systems of liquid water and alcohols
Photodissociation produced O/P3/ atoms detection and reaction rate measurements by resonance fluorescence scattering
Interstellar hydrogen ion production and destruction by electron recombination or photodissociation
Mariner 5 Venus exospheric Lyman alpha measurements for dayside temperature value, using molecular hydrogen photodissociation model
The quantum yield for CO2 photodissociation at 25 C was found to be 1.08 + or - 0.12 for direct photolysis at 1849 A and between 200 and 800 torr; 0.48 + or - 0.02 for the Hg 6(1 P 1) sensitized decomposition between 130 and 730 torr; and 0.16 + or - 0.05 for the direct photolysis at 2139 A and between 300 and 600 torr. At these wavelengths, there was insufficient energy found to produce O(1 D). The primary process used is CO2 + hv yields CO + O(3 P).