Distinguishing and controlling the rotation directions of CO molecules in even and odd rotational states

We experimentally utilize two linearly polarized femtosecond laser pulses, termed the alignment pulse and the control pulse, with specific polarization angles and time delays, to distinguish and control the ultrafast rotation of CO molecules in even and odd rotational states. The spatiotemporal evolution of the rotating CO molecules is tracked by measuring the time-dependent momentum distributions of ionic fragments resulting from Coulomb explosion, induced by a circularly polarized femtosecond laser pulse. Our results demonstrate that CO molecules in even and odd rotational states can be distinguished at rotational revivals, exhibiting opposite rotational directions. These rotational directions can be controlled by adjusting the polarization of the control pulse. The experimental results are supported by quantum numerical simulations.