A Brillouin light scattering study of the lambda transition in liquid sulphur

The dynamics of liquid sulphur have been investigated in the temperature region corresponding to the so-called lambda transition by means of Brillouin light scattering. Results of this work, together with ultrasonic spectroscopy and inelastic X-ray scattering results in literature, indicate that the main structural relaxation is slightly affected by the transition and suggest that the dramatic increase of shear viscosity is related to the onset of a low-frequency additional relaxation. Such a feature is commonly found in rubber-like materials and can be related to the polymerization of sulphur molecules across the transition.