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At least 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Electron-temperature dependence of dissociative recombination of electrons with CO(+)-(CO)n-series ions

A microwave afterglow mass spectrometer apparatus is used to determine the dependence on electron temperature T sub e of the recombination coefficients alpha sub n of the dimer and trimer ions of the series CO+.(CO) sub n. It is found that alpha sub 1 = (1.3 + or - 0.3)x 0.000001 (T sub e(K)/300) to the -0.34; and alpha sub 2 = (1.9 + or - 0.4)x 0.000001 (T sub e(K)/300) to the -0.33 cu cm/sec. These dependences on T sub e are quite different from those obtained previously for polar-cluster ions of the hydronium and ammonium series but are similar to that for simple diatomic ions.

Whitaker, M.↗
NASA NTRS1981

Electron-temperature dependence of dissociative recombination of electrons with CO/+/./CO/n-series ions

The dependence on electron temperature of the coefficients for electron recombination with molecular cluster ions of the carbon monoxide series, CO(+).(CO)n, is determined. A microwave discharge lasting approximately 0.1 msec was applied in 5-20 Torr neon containing a few tenths percent CO in an afterglow mass spectrometer apparatus, and the time histories of the various afterglow ions were measured. Expressions for the dependence of the recombination coefficients of the dimer and trimer ions CO(+).CO and CO(+).(CO)2 are obtained which are found to be significantly different from those previously obtained for hydronium and ammonium series polar cluster ions, but similar to those of simple diatomic ions.

Whitaker, M.↗
NASA NTRS1981

An experimental study of SO3 dissociation as a mechanism for converting and transporting solar energy

The high temperature catalytic dissocation of SO3 is an important chemical process being considered in the development and application of solar-thermal energy conversion, transport, and storage systems. A facility for evaluating chemical converter-heat exchangers at temperatures to 1000 C with high flow rates of gaseous SO3 feedstock has been assembled and operated on the NMSU campus. Several quartz and metal reactors containing different catalyst configurations have been tested. Descriptions of the test facility and of the reactors are given along with a presentation and discussion of experimental results.

Mccrary, J. H.↗
NASA NTRS1981

Non-thermal O/1D/ produced by dissociative recombination of O2/+/ - A theoretical model and observational results

Thermal and nonthermal O(1D) number density profiles are calculated. The two populations are assumed to be coupled by a thermalization cross-section which determines the loss and production in the nonthermal and thermal populations, respectively. The sources, sinks and transport of the two populations are used to model volume emission rate profiles at 6300 A. The 6300 A brightness measured by the Visible Airglow Experiment is then used to establish the presence of the nonthermal population and to determine the thermalization cross-section.

Schmitt, G. A.↗
NASA NTRS1984

Improved Coil for Hydrogen Dissociators

Flat coil has rigid printed circuit substrate. New coil structure minimizes RF electric field near glass walls of plasma vessel; therefore reduces direct electron bombardment of glass. Design lends itself well to high production and standardized dimensions.

Vessot, R.↗
NASA NTRS1983

Dissociative recombination of O2(+), NO(+) and N2(+)

A new L(2) approach for the calculation of the threshold molecular capture width needed for the determination of DR cross sections was developed. The widths are calculated with Fermi's golden rule by substituting Rydberg orbitals for the free electron continuum coulomb orbital. It is shown that the calculated width converges exponentially as the effective principal quantum number of the Rydberg orbital increases. The threshold capture width is then easily obtained. Since atmospheric recombination involves very low energy electrons, the threshold capture widths are essential to the calculation of DR cross sections for the atmospheric species studied here. The approach described makes use of bound state computer codes already in use. A program that collects width matrix elements over CI wavefunctions for the initial and final states is described.

Guberman, S. L.↗
NASA NTRS1983

The dissociation energy of Cu2 - Do we want to perform multi-reference singles and doubles CIs on many-electron systems?

Reference is made to a study by Hay and Dunning (1976), who showed that, for most problems, it is not necessary to perform full FOCI (first order configuration interaction); instead, only that subset of configuration state functions (CSFs) that differ by only one or two spin orbitals from any of a list of reference configurations need be used. This is referred to as POLCI. Calculations of the D(e) of Cu2 using both SDCI (singles and doubles configuration interaction) and POLCI models are presented. It is found that the size-consistency problems associated with SDCI cause an error in D(e), whereas the POLCI results are in excellent agreement with experiment. It is proposed that the orbitals be classified as inactive and active and that the inactive-inactive correlation be eliminated to reduce the size-consistency error. In addition, it is recommended that SDCI treatments be applied with caution to systems having a large number of electrons.

Bauschlicher, C. W., Jr.↗
NASA NTRS1984

The dissociation of OH and OD in comets by solar radiation

Calculations of the radiative lifetimes of cometary OH are presented as a function of the radial velocity of the comet and of the velocity distributions of the hydrogen and oxygen atoms produced by photodissociation of OH. The contribution of the photodissociation of OH to the emission of the red and green lines of atomic oxygen is assessed. An estimate is made of the lifetime of OD and of the velocity distribution of the deuterium atoms.

Van Dishoeck, E. F.↗
NASA NTRS1985

Dissociative and double photoionization cross sections of NO from threshold to 120 A

The partial photoionization cross sections for producing the NO(+) parent ion and the O(+), N(+), and NO2(+) fragment ions from neutral NO are presented from 120 to 614 A. The results indicate predissociation of the c(sup3) pi (21.72 eV) and B prime (sup 1) sigma (+) (22.73 eV) electronic states of NO(+). The photoionization threshold for double ionization was found to be 39.4 + or 0.12 eV.

Samson, J. A. R.↗
NASA NTRS1985

Hadron cross sections at ultra high energies and unitarity bounds on diffraction dissociation

It was shown that if unitarity bounds on diffractive cross sections are valid at ultra high energies then diffractive dominance models which ascribe the increase in total hadron-hadron cross sections to diffractive processes only are ruled out. Calculations also show that cosmic ray cross sections derived from air shower experiments at ultra high energies clearly rule out models for hadron-hadron cross sections with nat.log ns energy dependence and favor those with nat.log n(2)s variation.

Yodh, G. B.↗