The emission of electrons under the influence of chemical action. Part IV—The reactions of liquid NaK 2 with gaseous SOCl 2 , S 2 Cl 2 , SO 2 Cl 2 , HgCl 2 , sulphur dichloride and with mixtures of gases and a new method of determining the contact potential difference

Abstract

In two earlier papers, which we shall refer to as Part I and II in the sequel, we described a very detailed investigation of the electron emission phenomena which occur when the liquid alloy of sodium and potassium reacts with phos-gene, COGl 2 , at very low pressures. In Part II we also gave a brief account of some of our principal conclusions from the results of experiments in which 22 gases were examined. In a third paper, Part III, we gave a detailed description of the corresponding phenomena observed with a variety of gases, namely, Cl 2 , NOCl, HCl, Br 2 , I 2 , COS, N 2 O, and H 2 O. A comparison of the data obtained with Cl 2 , COCl 2 , and NOCl disclosed a linear relation between the dissociation energy involved in the reaction and the maximum energy of the emitted electrons. A theory of the way in which we supposed this connection to originate had already been given in Part II. With the particular purpose of testing further the generality of this relation, as well as of widening the basis of our information as to the details of the energy distribution among the electrons emitted in different reactions, we selected for our next experiments a group of gases containing chlorine. The gases chosen were SOCl 2 , S 2 Cl 2 , SO 2 Cl 2 , HgCl 2 , and S 2 G 4 . We expected that one of the immediate results of the reaction of these gases with the liquid alloy would be, as in the case of Cl 2 , COCl 2 , and NOCl, the adsorption of a Cl¯ ion on the surface of the alloy; consequently the same theory should apply to all of them. The parts of this paper which follow immediately are concerned with a description of the results of the experiments with these five additional gases containing chlorine. We next describe experiments which, we made with mixtures of COCl 2 with COS, and with S 2 Cl 2 , and of SOCl 2 with S 2 Cl 2 . The object of these was to test the additive property of the chemical electron emission. We then go on to describe a new method of determining the contact potential difference between the alloy drop and the surrounding platinum electrode in presence of the different gases. We regard the results given by this method as of great importance in establishing the interpretation of the experimental data on a firm basis. This is followed by an analysis of the electronic spectra of the gases to be described in this paper. The primary object of the analysis consists in identifying the different groups in a composite electronic spectrum with the corresponding mechanisms of the reaction; the analysis is conducted in the light of our previous experience with the reactions involving halogens and also in the light of some new general considerations of the kinetics and of the electronic yield of the chemical reactions. The electronic spectra, having been thus analysed, are then applied to test the fundamental relation between the dissociation energy, involved in a certain reaction, and the maximum energy of the emitted electrons of the group originating from the reaction with the corresponding mechanism. Finally we present the energy distribution functions obtained with the gases under consideration.