Abstract
In the layer structure MoS2, the oscillatory inter-band magneto-optic absorption has revealed a mass ratio of the order of 0.01. Theory is presented to show that this mass may be associated with the H-point of the Brillouin zone. Moreover, it is proposed that the origin of the mass is an instability of the equally-spaced layer arrangement giving rise to a distorted form with alternate layers displaced in the axial direction.