Rates of ion neutralization have been measured in hydrogen chloride, hydrogen bromide, and nitrous oxide by collecting the ions remaining in a defined v o l~~n~e at various times after ionization by a pulse of 120 k.v.p. X-rays. Values of the total homogeneous ion-ion recombination coefficient, rl, have been obtained for each gas over a range of pressures in the region 50 to 650 Torr. From a study of the effects of pressure and ion density, the relative rates of wall diffusion, mutual neutralization, and three-body neutralization have been deduced.

The homogeneous ion neutralization coefficient in SF6 has values of 1.0±0.1, 1.2±0.1, 1.1±0.1, and 1.2±0.7×10−6 cm3 s−6 respectively at 150, 356, 550, and 603 Torr for ions created by pulses of x rays. The results are compared with calculated three-body neutralization coefficients for monomer and dimer ions.

Communications to the Editor sweep study of a(s)-a field pioneered to a large extent by the measurements of Takahashi and Nagasawa. The same goes for the molecular weight dependence argued by NTN. True, low to medium values of a satisfactorily obey Fixman's equation6 a8 -1 -v MVa (9) but as Takahashi, Nagasawa, and coworkers point out themselves1-3 their high a's increase with M1/2 less rapidly than required by the above equation. (Unfortunately the relevant points are not reproduced in the figures given by the authors; still they may be easily extracted from the tabulated data.) On the other hand, as stated before, the wide sweep variation of a with Ml/t, for all m2 > 2, is quite adequately described by the author's eq 5.

The ionization yield from fast electron impact on DCI under radiolysis conditions at 200 to 650 Torr was found to be 1.006 + 0.023 times that from HCI. Also primary ionization processes were investigated by mass spectrometry. The relative abundance of Cl + from HCI near threshold at 17.4eV was about twice that from DCI, but processes with onset at and above 21.0 eV did not exhibit an isotope effect. The interpretation of the results and their implications concerning the mechanism of radiolysis of HC1 were discussed. Can. J. Chem., 52,359 (1974)

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