The Formation of Negative Ions in Gases Part II. CO2, N2O, SO2, H2S and H2O

The study of electron attachment has been extended to the gases CO2, N2O, SO2, H2S and H2O. No negative ions were observed in CO2. In N2O, below X/p = 2, no negative ions were formed, and the N2O molecule apparently has no electron affinity. For values of X/p>2, the electrons possessed sufficient energy to dissociate the molecule and negative ions, probably O-, were formed in increasing numbers. SO, showed an electron affinity forming negative ions with electrons of very low velocity. The probability of attachment decreased as X/P increased until an X/p of about 13 when an increase in probability of formation was noted. This is probably due to dissociation and formation of SO-. No negative ions were observed in H2S below an X/p of 6. For greater values of X/p negative ions were formed in increasing amounts presumably by a dissociation process with the formation of HS-. A similar behavior was observed in H2O at an X/p = 10, with the formation of OH-. Negative ion formation in H2O was also observed at low X/p and varied with the pressure of the gas. This is explained as being due to negative ion formation from small molecular aggregates existing near the point of condensation of the water.