Rotation of molecules induced by light

Abstract

In an earlier note to Nature (Aug. 25, p. 278) we ventured to suggest that the nebulosity or wings which accompany the original lines of the mercury arc after scattering in benzene liquid, are the effect of those collisions of the incident light-quanta with the molecules which result in a change of their rotational state. At the present time we are not very clear as to the conditions under which a spin may be set up in the molecule when it collides with a light-quantum. It appears, however, reasonable to suppose that the probability of such spin being induced should depend, among other factors, on the degree of optical anisotropy of the molecule.