Molecular mechanisms in liquids, which are responsible for the self-trapping of small-scale filaments of light, have been tested with regard to inertial response. Picosecond light pulses are found to self-trap even in viscous liquids and rigid glass where linear and rotational diffusional motions are frozen out. This and other evidence based on the characteristics of these filaments supports a molecular electronic distortion mechanism.

• Received 31 May 1968

DOI:https://doi.org/10.1103/PhysRevLett.21.267