Communication: Substantial impact of the orientation of transition dipole moments on the dynamics of diatomics in laser fields

Abstract

The formation of light-induced conical intersections (LICIs) between electronic states of diatomic molecules has been thoroughly investigated over the past decade. In the case of running laser waves, the rotational, vibrational, and electronic motions couple via the LICI giving rise to strong nonadiabatic phenomena. In contrast to natural conical intersections (CIs) which are given by nature and hard to manipulate, the characteristics of LICIs are easily modified by the parameters of the laser field. The internuclear position of the created LICI is determined by the laser energy, while the angular position is given by the orientation of the transition dipole moment (TDM) with respect to the molecular axis. In the present communication, using MgH+ as a showcase example, we exploit the strong impact of the orientation of the TDMs exerted on the light-induced nonadiabatic dynamics. Comparing the photodissociations induced by parallel or perpendicular transitions, a clear signature of the created LICIs is revealed in the angular distribution of the photofragments.

Photodissociation dynamics of the LiF molecule: Two- and three-state descriptions

“…An unexpected feature of the 2D results is the nonvanishing P 1 ang at the θ = 0 and π angles despite the zero dipole coupling. This effect was recently observed for another diatomic system with TDM perpendicular to the molecular axis [67], and it can be explained as follows: Similarly to the description given for the effect of a driving field while discussing the KER spectra, the interaction with the pump pulse leads to LICIs at the θ = 0 and π angles between the 1 -1 potential surfaces, although at different R value as the pump energy is different. The induced nonadiabatic effect provides an efficient route for the population transfer to the 1 state at these angles.…”

Polariton Induced Conical Intersection and Berry Phase

“…[22][23][24][25][26][27] Both enhanced non-adiabatic transitions and the geometric phase are attributed to as characteristic features of the presence of CIs. 8,25,26,28 In addition to the intrinsic CIs in polyatomic molecules, CIs can also be created by either standing 29,30 or running [31][32][33] laser waves in a diatomic molecule. This type of CIs are artificially created through light-matter interactions, and are commonly referred to as the light-induced conical intersection (LICI).…”

“…Thus, it is vital to reveal the characteristic features of these LI-CIs. Previous theoretical studies, employing the classical description of light, investigated the nature of the LICI in diatomic molecules 32,33,[35][36][37][38][39][40] and to what extent the geometric phase of the LICI is similar to the natural CIs for polyatomic molecule in a field free space. 31,[41][42][43] It has been demonstrated that LICI strongly impact the spectroscopic and dynamical properties of molecules, such as the molecular alignment, the photodissociation probability, molecular spectra, and the angular distribution of the dissociation photofragment.…”

Polaritonic states of matter in rotating cavity

“…As can be seen from Eq. (8), two LICIs between the potential energy surfaces (eigenvalues) of the Hamiltonian appear in a non-rotating cavity for θ = 0, π at the value of r where the condition V Σ (r) + hω c = V Π (r) is met, see also [46]. If the cavity rotates around Z, the number of LICIs doubles.…”

“…In the first step we freeze the nuclear motion of the molecule and consider the electronic-cavity matrix Hamiltonian for the system in a non-rotating cavity, i.e., the internuclear distance r and the rotational angles θ and ϕ are kept fixed and have the role of parameters. In the space of the above states this Hamiltonian is a 3 × 3 matrix, but depending on the polarization of the cavity, one can transform the components of the degenerate ψ Π 0 c state such that one component decouples resulting effectively in a 2 × 2 matrix, see, e.g., [46]. As we shall see below, in a rotating cavity the Hamiltonian cannot be reduced and stays a 3 × 3 matrix.…”