Manipulating field-free molecular alignment by v -shaped femtosecond laser pulses

We demonstrate theoretically that the shaped femtosecond laser pulse with a V-style spectral phase modulation can provide a well-established tool to control the maximal degree and temporal structure of the field-free molecular alignment. By properly designing these controlling parameters characterizing the V-style spectral phase modulation, we can effectively suppress the maximum degree of molecular alignment or reconstruct as that induced by the transform-limited laser pulse while the temporal structure of the molecular alignment keeps unchanged; we also can control the temporal structure of the molecular alignment with a desired shape and switch the molecular alignment and antialignment at any time delay for any temporal structure.