Nature 124, 794-794 (23 November 1929) | doi:10.1038/124794b0

The Second Spark Spectrum of Lead



THE second spark spectrum of lead was recently analysed by K. R. Rao and ourselves; and a preliminary report of the series regularities discovered was published in a paper (Ind. J. Phy., vol. 2, pt. 4, pp. 468-476.) We have since become aware of a similar publication by Smith (Proc. N. A. S., vol. 14, pp. 878-880; 1928). There is a good agreement between our results and those of Smith, except in the identification of I 3P - I 3S 1. Evidently he has our I 3 S as his I 3P1 Carrol has very irregular intensities for the lines suggested by him. The I 3S1suggested by us is supported by the location of the second series I 3 S - 2 3P, I 3D - 2 3P, and 2 3P -2 3 S. Furthermore, 1 3P - I 3S suggested by us is given additional support by the closeness with which it follows the irregular doublet law, for the isoelectronic sequences, Hg I, Tl II, and Pb III. An interchange of his levels I 3S1 and I 3P1 would probably bring the whole scheme into alinement with ours. As a result of our attempts to get further regularities, we have been able to get 2 3P -2 3D and 2 3P -2 3P as well.