The Nuclear Spin of Deuterium

By the methods of photographic photometry, the alternating intensities in emission of the $\ensuremath{\Delta}v=0$ sequence of the Fulcher bands of deuterium have been investigated in order to determine the nuclear spin. The alternation of intensities was determined for the $P$, $Q$ and $R$ branches of each of the 5 bands studied. The average value of $\frac{{g}_{s}}{{g}_{a}}$ obtained from 4 plates is 1.97\ifmmode\pm\else\textpm\fi{}0.03. This value agrees best with the theoretical ratio of 2 and a consequent nuclear spin of 1. Since the even rotational levels are more intense than the odd levels, the nucleus obeys Bose-Einstein statistics.