Publication coats assisted by the Air Force Cambridge Research Laboratories Release of barium vapor at high altitude provides a useful geophysical tool by forming a visible tracer for motions of ions and neutrals in the ionosphere. The excitation, ionization, and oxidation of atomic barium released in sunlight between 100 and 200 km altitude is examined in this paper. Observed spectral measurements of resonance Ba and Sr atoms, excited Ba atoms, Ba ions, and BaO molecules provide the basis for

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... stimating relative importance of the several processes. Excitation of ground-state barium to excited metastable levels with a time constant of l sec is followed by photoionization with a time constant of 30 sec. Oxidation of the metastables has an altitude-dependent time constant, ranging from a fraction of a second at 100 km to 40 see at 200 km. Thus oxidation dominates over ionization at low altitudes and limits observations of ion clouds to altitudes above about 150 km. When sea water samples are analyzed by the method of difference chromatography the composition differences are resolved into the coherent waves described by Helfferich and Klein. The predicted sequence of affinity cuts is found. Cation composition variations produced in the initial anion front by changes in total normality are found to be satisfactorily predicted by the theory. Similar variations produced by changes in the SOd/Cl ratio are found to be consistent with the theory and with previously verified consequences of a sea water model due to Garrels and Thompson. However the activity coefficient of K + is more strongly reduced by 502enrichment than the model predicts.