About Optical Control on Anisotropy of the Molecules in a Liquid: Orientational Anisotropy

The control on the orientational anisotropy of molecules in pure N,N-dimethylformamide at room temperature is demonstrated experimentally. To accomplish the optical control, the medium is non-resonantly excited with two successive linearly polarized laser pulses with a duration of 60 fs. The state of transient anisotropy is probed with the third pulse with the help of registering ultrafast optical Kerr effect using optical heterodyne technique and lock-in detector. The variations in the two parameters, the delay time between two pump pulses and the polarization angle between the directions of the pump pulses, are shown to ensure the control on the orientational anisotropy of the molecules in the subpicosecond region.