The mass of gas ions formed in a glow discharge and aged up to 10 5 impacts was determined by a Dempster type of mass-spectrograph. In hydrogen it is found that the primary ion, H2 + , changes within a few thousand collisions to H3 + , together with small quantities of H + . The nitrogen primary ions, N + and N2 + , attach to neutral molecules in about 10 5 impacts to form N3 4 " and N4 + . In pure oxygen the ions consist almost entirely of C>2 + with small quantities of 0 + . Air ions include all possible nitrogen and oxygen ions, the aged air ions consisting principally of N 3 + , N 4 + and 0 2 + together with the oxides of nitrogen. Charges are transferred from 02 + to NO, NO2 and N 2 0. Water vapor is particularly active in acquiring a charge by transfer and H 2 0 + ions may be most numerous in apparatus not baked out. No heavier clusters than N4 + were observed. No negative ions were observed. Some conclusions published in earlier work must be revised.

Coefficient of recombination of ions produced by x-rays as a function of the age and initial concentration of the ions. Measurement of the coefficient of recombination of ions in air and oxygen has been continued, with an improved form of the apparatus previously described by L. C. Marshall. Marshall's results in air have been checked, showing a sharp initial drop in the coefficient a for short time intervals ascribed to initial non-random distribution of the ions. Further measurements at longer time intervals have been made, using a new system of calculation whereby a is found as a function of r, the age of the ions, rather than t, the total time of recombination. In this case a does not drop to a constant value of about 0.8 to 0.9X 10~~6 as indicated by Marshall's results, but continues to drop off to values of 0.5 to 0.6 X 10~6 after the ions have aged for one second, and 0.3 to 0.4X 10~6 after two seconds. This is for a high initial concentration of ions of about 3.5 XlO 6 ions per cm 3 . With an initial concentration of 1.55 XlO 6 ions per cm 3 , a drops only to 1.15 X10~6 after a time of one second. In pure oxygen the values of a are in general higher than the corresponding ones for air, although they become equal at low inital concentrations.Interpretation of results and the absolute value of the coefficient in air. The results may be explained by assuming that heavy slow-moving ions are formed in increasing amounts as time goes on by reaction with impurities present. The faster ions are constantly being removed at a high rate by recombination, leaving the slow ions behind with a resulting increasingly low coefficient of recombination. It is possible that the ionizing agent produces nitric oxides, O3 or H 2 0 2 , which load up the ions. It is impossible to set accurately an absolute value of a in air, due to two disturbing factors: initial non-random distribution producing abnormally high values of a at short time intervals, and the loading up of the ions with impurities producing abnormally low values of a at long time intervals. At a time where these two factors have a minimum effect a has the value 1.4 ±0.1 X10" 6 , which is set as the closest approximation to an absolute value.

No abstract

A mass spectrograph analysis has been made of aged ions in mixtures of hydrogen and deuterium. The concentration of deuterium was varied from 84 percent to less than one percent. After drifting through 5 cm of gas at about 0.5 mm pressure, the ions were found to be over 95 percent triatomic; that is, H3+, H2D+, HD2+ and D3+. Measurement of the relative intensities of the triatomic ion peaks indicates a slightly greater number of H3+ and D3+ ions compared to H2D+ and HḊ2+ than would be expected from probability considerations if the H and D atoms behaved exactly alike. This tendency for like atoms to group together may be accounted for by taking cognizance of the proper equilibrium constant for the different types of diatomic molecules in the gas mixtures employed. There is no evidence of further preferential grouping in the formation of the triatomic ions from the primary molecular ions. The relative heights of the triatomic ion peaks may be used to determine the abundance of the isotopes in a sample of gas.