Simultaneous Ionization and Excitation of Diatomic Molecules by Impacts with Positive Ions and Excited Atoms

Abstract

A study of mixtures of helium, neon, and argon with carbon monoxide and nitrogen is made wherein it is demonstrated that impacts occur between a rare gas ion and a diatomic molecule leading to ionization and excitation of the latter. It is also shown that impacts of the second kind between excited helium and neon atoms and neutral carbon monoxide molecules, resulting in the simultaneous ionization and excitation of the latter, are possible. Experiments are described which show the effectiveness of either type of impact to be greatest when the energy difference is the least. These impacts are shown to explain several previously observed but unexplained effects in similar mixtures in glow dicharges. Two new bands in the Baldet-Johnson band system due to ionized carbon monoxide with edges at $\lambda 4454.95$, 4458.94, 4480.24, 4485.00; and 4494.30, 4498.31, 4519.89, 4524.89 are reported and six new edges and a new band at $\lambda 3413.14$, 3414.60; 3584.20, 3600.75; 4116.69, 4348.08; 5856.30, 5860.37, 5900.21, 5905.85 in the comet-tail system. The wave-lengths of the heads of all bands of these two systems observed in this investigation have been measured and an analysis of the systems is given. From a study of the intensity distribution of the negative band systems of carbon monoxide excited in He-CO and Ne-CO mixtures, the following deductions relative to the degree of excitation of the CO-ion in the two mixtures are made: In Ne-CO mixtures there are many more CO-ions in the 16.8 volt state than in the 20 volt state, but in He-CO mixtures the reverse is true. A study of the intensities of the individual comet-tail bands excited in He-CO and in Ne-CO mixtures under the same conditions shows that the exciting processes in He-CO mixtures are more effective in exciting the higher vibrational states of the comet-tail bands than they are in Ne-CO mixtures. The spectrum of carbon dioxide recently observed and reported by Fox, Duffendack and Barker has been shown to be due to the carbon dioxide ion.