v. Formation of negative ions by processes other than attachment in the gaseous phase at low X/po 17. Introduction. As early as 1912, J. J. THOMSON [32J in his first mass spectro graph observed negative ions of 0-, Cl-, H- and what he believed to be N-. He at first ascribed these to possible dissociation of polar gaseous compounds by electron impact but control studies using ionization at low energies in glow discharges indicated that this was not the origin. O. W. RICHARDSON [33J in his book on emission of electricity from hot bodies reported negative ions to come from hot salts. From there on many experimental studies over the years indicated that negative ions could be formed by various processes. By the middle nineteen hundred and thirties the data fairly clearly identified several processes as being active and MASSEY and SMITH [34J developed the theory underlying some of them. More data are summarized in MASSEY'S excellent little monograph on Negative Ions and in )L\SSEY and BURHOP'S recent book [35]. Since that period, stimulated by various investigations and certain industrial problems, very careful studies of the appearance of such ions by mass spectrograph have been carried out in the laboratory of K. G. EMELEUS in Belfast by SLOANE and his co-workers [3J that haw clarified the questions and indicated what ions have been observed and something of the processes at work.

Inhalt
Thermionic Emission.- A. Scope and objectives.- B. Historical highlights.- C. Theory.- D. Applications of theory to experiments on thermionic emission.- Tables.- Appendix 1: Thermionic constants.- Appendix 2: Some useful equations from statistical theory of free electrons.- Field Emission.- I. Introduction.- II. Theory of field emission.- III. Experimental results.- IV. Field emission microscopy.- V. Field emission of positive ions.- References.- Sekundärelektronen-Emission fester Körper bei Bestrahlung mit Elektronen.- A. Einführung.- B. Energieverteilung der Sekundärelektronen.- C. Die Anzahl der Sekundärelektronen (Ausbeute).- D. Weitere Eigenschaften von Sekundärelektronen.- E. Daten über die Bewegung langsamer Elektronen in festen Körpern.- F. Theoretische Ansätze zur Deutung der Sekundäremission.- Literatur.- Photoionization in gases and photoelectric emission from solids.- A. Photoionization in gases.- B. Photoelectric emission from solids.- Motions of Ions and Electrons.- I. Electron and ion orbits.- II. The Langevin equation.- III. The Boltzmann equation.- IV. Boltzmann transport equation.- V. The Fokker-Planck equation.- General references.- Formation of Negative Ions.- I. Fundamentals.- The Recombination of Ions.- I. Basic relations.- II. The measurement of the coefficient.- III. Experimental results and the theories of the recombination coefficient.- References.- Ionization in Gases by Electrons in Electric Fields.- A. Introduction.- B. Ionization in uniform electric fields.- C. The non-uniform electric field.- D. Ionization in combined electric and magnetic fields.- Secondary Effects.- References.- Sachverzeichnis (Deutsch-Englisch).- Subject Index (English-German).