Open AccessThe nuclear spins and magnetic moments of the isotopes of antimony
Author(s) -
S. Tolansky
Publication year - 1934
Publication title -
proceedings of the royal society of london. series a, containing papers of a mathematical and physical character
Language(s) - English
Resource type - Journals
eISSN - 2053-9150
pISSN - 0950-1207
DOI - 10.1098/rspa.1934.0147
Subject(s) - antimony , isotope , cathode , atomic physics , spins , physics , spectral line , chemistry , nuclear physics , materials science , condensed matter physics , metallurgy , astronomy
The first detailed examination of the fine structures occurring in the visible lines of the Sb II spectrum was made by Badami, who reported extensive structures in many lines. Badami attempted to excite the Sb II spectrum in a hollow cathode discharge, but even a current of 0⋅4 amp failed to produce sufficiently strong lines. As a source he therefore used a relatively high current arc (carrying 3-5 amps) which necessarily broadened each component so that serious blending introduce considerable ambiguity in analysis. According to Aston, antimony consists only of two isotopes, 121 and 123, whose abundance ratio is 100 : 78⋅5. Badami concluded that the nuclear spin of the 121 isotope is 5/2 and that of the 123 isotope is 7/2. However, a critical comparison between the experimental data he published, and the theoretically predicted patterns based upon this assumption, shows so much ambiguity in interpretation, that a re-examination of the spectrum was undertaken. It was apparent that the source to be used must give sharper components than the arc as used by Badami, and for this purpose a hollow cathode appeared to be most suitable. When the author was engaged upon an analysis of the As II fine structures, he encountered the same difficulty as Badami, in failing to excite a sufficiently strong As II discharge in a cooled hollow cathode. Since arsenic and antimony are so closely related in the Periodic Table, it was thought that the phenomenon might be due to inappreciable sputtering in both elements. However, whilst recently engaged upon intensity measurements in the As II structures (together with J. F. Heard) the author found it possible to produce an intense As II spectrum in a cooled hollow cathode, provided the arsenic was free from oxide. This at once suggested that an oxide free antimony hollow cathode ought to yield good results. This was indeed found to occur, and with only-seventh of an ampere a brilliant Sb II spectrum was excited. The source is much superior to the arc, not only giving sharper lines, but also appearing to be much stronger.