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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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NASA NTRS1972

The formation of interstellar diatomic molecules

Reactions between atoms and ions of the interstellar medium and vibrationally excited molecular hydrogen are shown to produce a specific set of molecules. Molecules such as CO and CN can readily be produced in abundances greater than those of corresponding hydrides. When quantified in a simple manner the equilibrium density of molecules compares well with the observed values for the star Oph.

Stecher, T. P.↗
NASA NTRS1972

Electric dipole moment of diatomic molecules by configuration interaction. IV.

The theory of basis set dependence in configuration interaction calculations is discussed, taking into account a perturbation model which is valid for small changes in the self-consistent field orbitals. It is found that basis set corrections are essentially additive through first order. It is shown that an error found in a previously published dipole moment calculation by Green (1972) for the metastable first excited state of CO was indeed due to an inadequate basis set as claimed.

Green, S.↗
NASA NTRS1972

The formation of diatomic molecules in interstellar clouds.

The formation of the classical interstellar molecules CH, CH(+), and CN is investigated, giving attention to the chemistry of moderate-density interstellar clouds. An H I region is considered in the model employed in the study. The major constituents in the region are atoms or ions because of the intensity of the UV radiation field. Aspects of radiative association are discussed together with chemical reactions, the electronic states and optical properties of CH and CH(+), and photodissociation rates.

Solomon, P. M.↗
NASA NTRS1974

The polarizability of diatomic helium

The calculation of the electric dipole polarizability tensor of the He 2 dimer is described, and the results are used in the computation of several dielectric and optical properties of helium gas, at both high (322 K) and low (4 K) temperatures. The properties considered are the second dielectric virial coefficient, the second Kerr virial coefficient, and the depolarization ratio of the integrated intensities for the Raman scattering experiments. The thesis consists of five parts: the polarizability and various properties are defined; the calculation of the polarizability in the long-range region in terms of a quantum mechanical multipole expansion is described; the calculation of the He2 polarizability in the overlap region via coupled Hartree-Fock perturbation theory is described; the calculation of the quantum pair distribution function for both the He-3 and He-4 isotopes at 4 K is discussed; and the calculated values of the properties of helium gas are given.

Fortune, P. J.↗