Abstract
Conical intersections between electronic potential energy surfaces are paradigmatic for the study of nonadiabatic processes in the excited states of large molecules. However, since the corresponding dynamics occurs on a femtosecond timescale, their investigation remains challenging and requires ultrafast spectroscopy techniques. We demonstrate that trapped Rydberg ions are a platform to engineer conical intersections and to simulate their ensuing dynamics on larger length scales and timescales of the order of nanometers and microseconds, respectively; all this in a highly controllable system. Here, the shape of the potential energy surfaces and the position of the conical intersection can be tuned thanks to the interplay between the high polarizability and the strong dipolar exchange interactions of Rydberg ions. We study how the presence of a conical intersection affects both the nuclear and electronic dynamics demonstrating, in particular, how it results in the inhibition of the nuclear motion. These effects can be monitored in real time via a direct spectroscopic measurement of the electronic populations in a state-of-the-art experimental setup.
Highlights
Conical intersections between electronic potential energy surfaces are paradigmatic for the study of nonadiabatic processes in the excited states of large molecules
We demonstrate that trapped Rydberg ions are a platform to engineer conical intersections and to simulate their ensuing dynamics on larger length and time scales of the order of nanometers and microseconds, respectively; all this in a highly controllable system
We study how the presence of a conical intersection affects both the nuclear and electronic dynamics demonstrating, in particular, how it results in the inhibition of the nuclear motion
Summary
Two ions are confined by a harmonic trapping potential in the X − Z plane. From the ground state |g , each ion is excited to the two Rydberg states |↓ = |nS and |↑ = |nP. In the BO approximation, the nuclei oscillate around the equilibrium position r0 of the relative motion and in the CM reference frame the nuclear density N (q, t) = k |φk (q, t)|2 moves from one minimum of U− (q) to the other The effects of this motion can be directly observed in the time evolution of the diabatic populations nk (t), which can be monitored in real-time via a spectroscopic measurement of the Rydberg states. An external static electric field and a tailored exchange interaction potential between Rydberg states fully control the shape of the two crossing PESs and the location of the CI. [49] See Supplemental Material for details on the derivation of Eq (4), the preparation of the nuclear initial state φsresl (q), the tailored exchange interaction potential Vex (r), the BO approximation, and the generalization to a three-ion setup.
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