Question

The deuteron is a bound state of neutron and proton and has spin 1 and positive parity. Prove that it can exist only in the ³S₁ and ³D₁ states.

Answer 1

The deuteron which is the nucleus of deuterium (heavy hydrogen) consists of one proton and one neutron. Since the parity of neutron and proton are +1, that of deuteron is also +1. Spin of deuteron is 1, and l = 0 mostly, with 4% admixture of l = 2 so that the parity determined by (−1)^l = +1 for l = 0 or 2. The deuteron is in a state of total angular momentum J = 1. Thus J^p = 1⁺. Using the spectroscopic notation ^2s+1L_J, deuteron’s state is described by ³S₁ and ³D₁.