KCS

Quasi-free electron bound in atoms or molecules often plays a role of key initiator in various chemical reactions. Manipulating the bound character of excess electron may provide dynamic control of subsequent reaction rate or pathway, yet it is still in its infancy on the polyatomic molecular systems. Herein, we present the experimental observation of the dynamic Stark effect on non-valence bound states (NBS) of polyatomic molecular anions by exploiting the strong picosecond laser pulse. As the non-valence electron is weakly bound in neutral core by long-range potentials (charge-dipole or charge-quadrupole interaction), excess electron in NBS exhibits the ponderomotive blue-shift induced by the external oscillating electromagnetic field. Quasi-free quadrupole-bound electron is found to be more susceptible with respect to the laser field compared to the dipole-bound electron, implying the diffuse and more polarizable nature of quadrupole-bound state (QBS) compared to the dipole-bound state (DBS). This finding promises the quantum manipulation of polyatomic systems by employing the ponderomotive effect induced by oscillating laser field in the near future. [1] D. H. Kang, S. An and S. K. Kim, Phys. Rev. Lett. 125, 093001 (2020). [2] D. H. Kang, J. Kim, M. Cheng and S. K. Kim, J. Phys. Chem. Lett. 2021, 12, 1947-1954. [3] D. H. Kang, J. Kim, H. R. Noh and S. K. Kim, Nat. Commun. 12, 7098 (2021).