Importance of the lowest-lying <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si34.gif" overflow="scroll"><mml:mrow><mml:mi mathvariant="normal">Π</mml:mi></mml:mrow></mml:math> electronic state in the photodissociation dynamics of LiF

Tóth, Attila; Badankó, Péter; Halász, Gábor J.; Vibók, Ágnes; Csehi, András

doi:10.1016/j.chemphys.2018.05.002

Cited by 12 publications

(12 citation statements)

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“…To calculate the potential energy, the dipole moment, and the NAC curves of the LiF molecule ( figure 1(b)), the program packages Molpro [55] was used. These quantities were calculated at the MRCI/CAS(6/12)/aug-cc-pVQZ level of theory [56]. In particular, τ(R) has been computed by finite differences of the MRCI electronic wave functions.…”

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Ultrafast dynamics in the vicinity of quantum light-induced conical intersections

et al. 2019

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Nonadiabatic effects appear due to avoided crossings or conical intersections (CIs) that are either intrinsic properties in field-free space or induced by a classical laser field in a molecule. It was demonstrated that avoided crossings in diatomics can also be created in an optical cavity. Here, the quantized radiation field mixes the nuclear and electronic degrees of freedom creating hybrid fieldmatter states called polaritons. In the present theoretical study we go further and create CIs in diatomics by means of a radiation field in the framework of cavity quantum electrodynamics. By treating all degrees of freedom, that is the rotational, vibrational, electronic and photonic degrees of freedom on an equal footing we can control the nonadiabatic quantum light-induced dynamics by means of CIs. First, the pronounced difference between the the quantum light-induced avoided crossing and the CI with respect to the nonadiabatic dynamics of the molecule is demonstrated. Second, we discuss the similarities and differences between the classical and the quantum field description of the light for the studied scenario.The dynamics initiated in a molecule by absorbing a photon is often described in the Born-Oppenheimer (BO) or adiabatic approximation [1], where the electronic and nuclear degrees of freedom are treated separately. However, in some nuclear configurations called conical intersections (CIs) the mixing between the electronic and nuclear motions are very significant [2][3][4][5][6]. Owing to the strong nonadiabatic couplings (NACs) in the close vicinity of these CIs the BO approximation breaks down. It is well-known that these CIs have a significant impact on several important photo-dynamical processes, such as vision, photosynthesis, molecular electronics, and the photochemistry of DNA [7][8][9][10][11]. During the dynamics the CIs can serve as efficient decay channels for the ultrafast transfer of the populations. In the following we call these CIs, which originate from the field free electronic structure, natural CIs.Nonadiabatic effects can also appear when molecules are exposed to resonant laser light. The electric field can couple to two or more electronic states of the molecule via the non-vanishing transition dipole moment(s) [12][13][14][15]. This results either in a light-induced avoided crossing (LIAC) or a light-induced conical intersection (LICI) depending on how many nuclear degrees of freedom are involved in the field induced process [16]. In case of poly atomic molecules a sufficient number of vibrational degrees of freedom are always present to span a twodimensional branching space (BS), which is indispensable to the formation of LICI. In the case of diatomics one always has to find a proper second degree of freedom (DOF) which can act as a dynamical variable to form a BS. As the molecule rotates [17][18][19], the rotational angle between the molecular axis and the light polarization axis can serve as the missing DOF for establishing the BS [20].Nonadiabatic effects can arise in an optical or mi...

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Ultrafast dynamics in the vicinity of quantum light-induced conical intersections

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“…The situation of the Π 1 state is more interesting. The fundamental difference here is that the TDM with the ground state is perpendicular to the molecular axis [42]. This means that the two states are coupled in the region where the control field least distorts the potential surfaces (see again Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Lithim fluoride along the other alkali-halides have been a popular testing ground for nonadiabatic dynamics during the photodissociation of these molecules due to the avoided crossing (AC) between their lowest lying 1 Σ + electronic states. In our previous works on this system we showed that a realistic theoretical description must also include the first 1 Π state [42,43]. Accordingly, in the present investigation we model the LiF molecule as a three-level system considering the 1 1 Σ + , 2 1 Σ + and 1 1 Π electronic states, labeled throughout the paper as Σ 1 , Σ 2 and Π 1 .…”

Section: The Physical Situation and Methodsmentioning

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“…The solutions of the TDSE were then used to calculate the populations of the employed electronic states [42], the kinetic energy release spectra (KER) and the angular distribution of the molecular fragments [57]. The electronic state populations are obtained as:…”

Section: Calculated Quantitiesmentioning

confidence: 99%

“…In the present work our showcase example is the lithium fluoride molecule, therefore the control procedure relies on the dipole limit. The LiF molecule has already been studied in our former works [42,43] where we discussed the role played by the lowest-lying Π electronic state in the photodissociation of the molecule through the population dynamics, the angular distribution and the kinetic energy release (KER) spectra of the photofragments. Describing appropriately the light-induced nonadiabatic phenomena the rotational degree of freedom has already been taken into account as dynamical variable in those works.…”

Section: Introductionmentioning

confidence: 99%

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Control of photodissociation with the dynamic Stark effect induced by THz pulses

Tóth

Csehi

Halász

et al. 2020

Phys. Rev. Research

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We demonstrate how dynamic Stark control (DSC) can be achieved on molecular photodissociation in the dipole limit, using single-cycle (FWHM) laser pulses in the terahertz (THz) regime. As the laser-molecule interaction follows the instantaneous electric field through the permanent dipoles, the molecular potentials dynamically oscillate and so does the crossings between them. In this paper, we consider rotating-vibrating diatomic molecules (2D description) and reveal the interplay between the dissociating wave packet and the dynamically fluctuating crossing seam located in the configuration space of the molecules spanned by the R vibrational and θ rotational coordinates. Our showcase example is the widely studied lithium-fluoride (LiF) molecule for which the two lowest Σ states are nonadiabatically coupled at an avoided crossing (AC), furthermore a low-lying pure repulsive Π state is energetically close. Optical pumping of the system in the ground state thus results in two dissociation channels: one indirect route via the AC in the ground Σ state and one direct path in the Π state. We show that applying THz control pulses with specific time delays relative to the pumping, can significantly alter the population dynamics, as well as, the kinetic energy and angular distribution of the photofragments.

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Dissociation in strong field: A quantum analysis of the relation between angular momentum and angular distribution of fragments

Ezra

Kallush

Kosloff

2020

Chemical Physics Letters

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Importance of the lowest-lying Π electronic state in the photodissociation dynamics of LiF

Cited by 12 publications

References 51 publications

Ultrafast dynamics in the vicinity of quantum light-induced conical intersections

Ultrafast dynamics in the vicinity of quantum light-induced conical intersections

Control of photodissociation with the dynamic Stark effect induced by THz pulses

Dissociation in strong field: A quantum analysis of the relation between angular momentum and angular distribution of fragments

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