On the interpretation of the Q-branch of hydrogen in water

The Raman Q branch of hydrogen dissolved in water is interpreted by means of a theory based on perturbative methods. Consistent with experimental results on pure rotational S (j) lines, in the theory we assume that the shifts of the lines composing the Q branch do not depend on the rotational states. It is found that an important mechanism determining the structure of the Q branch is the motional narrowing effect, particularly for the transitions involving orthohydrogen. A simple model of the Q branch allows the estimation of the rotational and vibrational relaxation properties of hydrogen in solution with water.