  We report the first experimental observation of non-adiabatic field-free
orientation of a heteronuclear diatomic molecule (CO) induced by an intense
two-color (800 and 400 nm) femtosecond laser field. We monitor orientation by
measuring fragment ion angular distributions after Coulomb explosion with an
800 nm pulse. The orientation of the molecules is controlled by the relative
phase of the two-color field. The results are compared to quantum mechanical
rigid rotor calculations. The demonstrated method can be applied to study
molecular frame dynamics under field-free conditions in conjunction with a
variety of spectroscopy methods, such as high-harmonic generation, electron
diffraction and molecular frame photoemission.
