Observation of the Ponderomotive Effect in Non-Valence Bound States of Polyatomic Molecular Anions

Abstract

The ponderomotive effect in the non-valence bound states has been experimentally demonstrated for the first time, giving the great promise for the manipulation of the polyatomic molecules by the dynamic Stark effect. Entire quantum levels of the dipole-bound state (DBS) and quadruple-bound state (QBS) of the phenoxide (or 4-bromophenoxide) and 4-cyanophenoxide anions, respectively, show the clear-cut ponderomotive blue-shifts in the presence of the spatiotemporally overlapped non-resonant picosecond control laser pulse. The quasi-free electron in the QBS is found to be more vulnerable to the external oscillating electromagnetic field compared to that in the DBS, suggesting that the non-valence orbital of the former is more diffusive and thus more polarizable compared to that of the latter.

Experimental Observation of the Resonant Doorways to Anion Chemistry: Dynamic Role of Dipole-Bound Feshbach Resonances in Dissociative Electron Attachment

“…Since it was firstly conceived by Fermi and Teller in 1947, 1 the dipole-bound state (DBS) of the anion has been both extensively and intensively investigated for many recent decades in terms of its structure and dynamic role [2][3][4][5] as its study becomes increasingly important for understanding the whole anion chemistry and physics in many aspects. [6][7][8] The lower limit of the dipole moment for the DBS formation had been initially predicted to be 1.627 D, although it seems to be now widely regarded (as a rule of thumb) that the excess electron could be attached to the neutral core when its dipole moment exceeds ~ 2.5 D. [9][10][11] It should be emphasized though that the nature of the binding force between the excess electron and neutral core seems to be not straightforward as much as the literal meaning of the DBS may imply. Namely, the interaction potential is rather complex as all the possible monopole-multipole (such as dipole or quadruple) interactions as well as the correlation effect should contribute corroboratively to the binding dynamics of the excess electron to the neutral core though the extents of their contributions should vary depending on the particular chemical systems under various circumstances.…”