Holding and spinning molecules in space

We illustrate, experimentally and theoretically, a laser-based method to control the rotations of polyatomic molecules in 3D space. A linearly polarized nanosecond pulse strongly aligns the most polarizable axis of an asymmetric top molecule along its polarization axis while an orthogonally polarized, femtosecond pulse sets the molecules into controlled rotation about the aligned axis. As a result, strong three-dimensional (3D) alignment occurs shortly after the femtosecond pulse and is repeated periodically, reflecting coherent revolution about the molecular axis. Our method opens new directions for research in orientationally confined complex molecules.