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Our work for the AFOSR has three primary components: Development of new quantum theory for the accurate description of molecular structure and spectra. Implementation of this new theory into general purpose computer programs (ACES II and pralel ACES III) to make it possible for many investigators, besides ourselves, to readily apply these new methods to problems of their interest. Application of these new methods to challenging molecules chosen to test the new methods, and to other systems of interest to AFOSR. These include high energy, density molecules, where the new methods allow an assessment of their energy content, stability, possible synthetic paths, activation barriers, and provide spectroscopic fingerprints for identification. We also make applications of interesting clusters, atmospheric systems, potential interstellar molecules, and to gas phase molecular reactions of the sort that can occur in flames., The original document contains color images.

The energy required to maintain an electric discharge in a gas is expended initially in the excitation and ionization of ground state atoms or molecules through inelastic collisions with energetic electrons. In the rare gases, a part of this energy is trapped temporarily in atomic and molecular metastable states. Investigations of the multitude of reactions undergone by these active species in rare gas discharges and afterglows were carried out toward the ultimate end of controlling these reactions, toward stabilizing and concentrating the active species. The report summarizes the results of the research. The very practical goal, on the one hand, was the production of a useful, though 'exotic', propellant and, on the other, the acquisition of basic information useful in understanding chemical reactions in rocket exhausts, the upper atmosphere, lasers, etc. The program of research that was followed included a very direct experimental approach to the problem of condensation and stabilization of metastable helium, together with long-range basic investigation seeking to determine the mechanisms for the many reactions carried out by these active species, to measure their rate constants and the effects of gas temperature, gas pressure, electron temperature, electron densities, impurities, etc. These reactions were investigated in a number of different types of active discharges and afterglows. (Author)

A literature survey and evaluation is presented in two volumes covering the areas, free radicals, metastable species and activated hydrocarbon. The discussion is confined to, and the abstracts are pertinent to, the use of the above species as propellants. The following conclusions were reached by the evaluation: While energies of the magnitude capable of producing 550 seconds specific impulses in propellants are theoretically achievable from free radicals, metastable excited species and activated hydrocarbon insufficient knowledge exists to determine whether a propellant is possible. Current knowledge would not warrant a propellant development program in any of the areas. Needed free radical research includes study of synthesis methods, activation energies and matrix composition. Needed metastable research includes gas phase studies of the kinetics of the helium molecule, oxygen metastables and hydrogen metastables at 77 and 4 K. Needed metastable research also includes condensed phase studies to identify unknown species in a neon matrix, to trap helium species in liquid helium and to convert singlet lithium hydride into triplet. Activated hydrocarbon research needs to center on adequate analytical and calorimetric techniques to unequivocally establish the nature of the phenomenon observed. The probability of success in each area can only be considered slight based on past experimental performance., See also Volume 2, AD-805 440.

An experimental program was undertaken to demonstrate the feasibility of trapping metastable electronic states by the techniques of matrix isolation. Metastable molecules of NH, BH, AlH, N2 and O2 were produced in the gas phase using discharge techniques or high temperatures and the resulting species trapped in a matrix at liquid helium temperatures. Attempts to produce and trap these metastable species were also carried out by electron bombardment or by U.V. irradiation of the appropriate matrix isolated molecule. Although no conclusive evidence for the long-time stabilization of an electronically metastable molecule was obtained, indications particularly in oxygen would suggest the need for further work. (Author)