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

Abstract

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. SO₂ 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.