Emergent Energy of Photoelectrons in Potassium Vapor.

to be between 0.66 and 0.79 volt. 'From the limit for atomic ionization, 2856 A, which corresponds to 4.32 volts, the dissociation potential of the neutral molecule is found to be 0.42 volt. This potential has been estimated by Carelli and Pringsheim6 to have a most probable value of 0.61 volts, so that the result obtained above is apparently somewhat low. A correction of the 2610 A limit for slit width would be in the' right'direction, but the amount i§uncertain. 'We see from the above that the dissociation potential of the ioniked molecule is apparently larger than that for the neutral molecule. If the band data for' the ionized molekule were available, the dissociation potential might possibly be obtained from the convie'rgence frequency of the oscillation levels, as was done by Carelli and Pringsheim for the neutral molecule. However, the writer can find no observations upon the spectra of the ionized molecule. Any atomic ionization would seem to be obscured by the molecular ionization. It is hoped that the work on potassium can be repeated either by the method of Kunz and Williams or by the methbd of Foote and Mohler. The writer is indebted to Professor J.' Franck for suggestions as to the interpretation of the above results. 1 Kunz and Williams, Phys. Rev., 22, 456, 1923. 2 Foote and Mohler, Ibid., 26, 195, 1925. 3 Williamson, Ibid., 21, 107, 1923. 4Samuel, Zeit. Phys., 29,209, 1924. 'Lawrence, Phil. Mag., 50, 345, 1925. Carelli and Pringsheim, Zeit. Phys., 44, 643, 1927.