Molecules in Intense Laser Fields: Applications

Bandrauk, A. D.; Aubanel, Eric; Chelkowski, Szczepan

doi:10.1002/9783527619436.ch25

Cited by 30 publications

(34 citation statements)

References 31 publications

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“…(Maximum intensities are given in W/cm 2 .) feature can easily be explained borrowing the light-induced potential (LIP) picture [19]. The molecules are exposed to small and intermediate light intensities and follow the diabatic dissociation path, while for high enough intensities they rather tend to follow the adiabatic path.…”

Section: Resultsmentioning

confidence: 99%

“…One of the clearest observable manifestation of the topological or Berry phase in a molecular system is the appearance of a quantum interference effect [17,18]. In order to illustrate this fundamental effect for the present LICI situation, we have chosen as an explicit example the photodissociation of the D 2 + molecule, which has been extensively studied for more than two decades [19][20][21][22][23][24]. In addition, it has also an advantage: Due to its relative simplicity one can study the new light-induced nonadiabatic phenomena separately from other processes.…”

Section: Introductionmentioning

confidence: 99%

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Nuclear-wave-packet quantum interference in the intense laser dissociation of the D2+molecule

et al. 2013

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Recently it has been recognized that electronic conical intersections in molecular systems can be induced by laser light even in diatomics. As is known a direct consequence of these accidental degeneracies is the appearance of nonadiabatic effects which has a strong impact on the nuclear quantum dynamics. Studying the photodissociation process of the D 2 + molecule, we report here some observable quantum interference phenomena that arise from the topological singularity induced by a strong laser field.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nuclear-wave-packet quantum interference in the intense laser dissociation of the D2+molecule

et al. 2013

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“…Our study has, however, been limited to two electronic channels with no account of the rotation. Although the introduction of this degree of freedom can significantly affect the dissociation rates [17], we have previously shown [9] that, through a shift in the critical intensities, which can be explained as due to a scaling law, the zero-width phenomenon persists even when introducing further channels needed to account for the rotation. Within these model limitations, it is important to emphasize that the proposed strategy is robust, generic, and experimentally feasible.…”

Section: -3mentioning

confidence: 99%

Proposal for laser purification in molecular vibrational cooling using zero-width resonances

et al. 2013

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Intense-field molecular photodissociation offers the possibility to define resonances of zero width for particular intensities at given wavelengths. We show how a laser pulse can be shaped to fulfill, at all times, the conditions leading to a zero width for a particular resonance originating from a field-free vibrational state. The solution of the time-dependent Schrödinger equation confirms that only this state survives after the pulse is off. This is the basis for a purification procedure leading to population left only in a single state chosen at will. Purification, to get a single vibrational (or rotational) state out of an ensemble of initial ones, is an important issue in the laser control of molecular dynamics. In particular, molecular rovibrational cooling is a major challenge which necessitates a selective preparation of a single rovibrational state starting from an initial distribution, either thermal or resulting from photoassociation [1]. Among other techniques, vibrational cooling has experimentally been achieved referring to blackbody-radiation-assisted lasers [2,3] or optical pumping by broadband femtosecond lasers [4]. In particular, methods involving photoassociation of ultracold atoms are able to produce translationally cold tightly bound molecules in a given electronic state. Additional sequences of shaped laser pulses are used to transfer most of these molecules in their ground vibrational state. All these processes involve a decay mechanism which describes the unavoidable entropy flow, a key concept in purification [5].For this purpose, we have recently proposed an adiabatic vibrational population transport mechanism using exceptional points (EPs) corresponding to two coalescing resonances for a specific laser wavelength and intensity [6]. A chirped pulse encircling the EP monitors the vibrational transfer between two adjacent resonances originating from field-free vibrational states v + 1 and v. The residual populations, after the pulse is over, could then be transferred step by step to state v = 0, using successive pulses. Contrary to a stimulated Raman adiabatic passage (STIRAP) technique which, by itself, is not fully appropriate for the purification purpose as it does not offer a dissipative channel where the entropy goes, this cooling strategy clearly involves a dissociative process. But it suffers from a compromise to ensure the underlying adiabatic transport. In particular, a long pulse duration to fulfill the requirement of adiabaticity may have, as a consequence, * osman.atabek@u-psud.fr † Also at U. F. R. an important depletion of the overall molecular population through photodissociation. A much more robust purification technique that we propose in this Rapid Communication is to start from a given vibrational distribution and to appropriately shape a single laser pulse, such as to efficiently photodissociate all vibrational states, with the exception of one. The entropy flow is merely associated with the photodissociation process. The mechanism we are referring to when shaping su...

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“…In particular, the potential energy surface of the molecule can be severely deformed in the presence of the fields, generating light-induced potentials [26][27][28][29]. Then, the energy eigenstates of the field-free Hamiltonian are not a very useful basis to follow the dynamics of the system.…”

Section: Introductionmentioning

confidence: 99%

Protecting and accelerating adiabatic passage with time-delayed pulse sequences

Sampedro

Chang

Solá

2016

Phys. Chem. Chem. Phys.

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Using numerical simulations of two-photon electronic absorption with femtosecond pulses in Na2 we show that: i) it is possible to avoid the characteristic saturation or dumped Rabi oscillations in the yield of absorption by time-delaying the laser pulses; ii) it is possible to accelerate the onset of adiabatic passage by using the vibrational coherence starting in a wave packet; and iii) it is possible to prepare the initial wave packet in order to achieve full state-selective transitions with broadband pulses. The findings can be used, for instance, to achieve ultrafast adiabatic passage by light-induced potentials and understand its intrinsic robustness.

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Molecules in Intense Laser Fields: Applications

Cited by 30 publications

References 31 publications

Nuclear-wave-packet quantum interference in the intense laser dissociation of the D2+molecule

Nuclear-wave-packet quantum interference in the intense laser dissociation of the D2+molecule

Proposal for laser purification in molecular vibrational cooling using zero-width resonances

Protecting and accelerating adiabatic passage with time-delayed pulse sequences

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