Ionisation of H 2 O by a strong ultrashort XUV pulse: a model within the single active electron approximation

Galstyan, A.; Popov, Yuri V.; Janssens, N.; Mota-Furtado, F.; O’Mahony, Patrick; Decleva, Piero; Quadri, Nicola; Чулуунбаатар, О.; Piraux, Bernard

doi:10.1016/j.chemphys.2018.02.014

Cited by 3 publications

(5 citation statements)

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“…Time-dependent calculations for H 2 O were performed in the single-active-electron approximation [54,55], strongfield approximation [56], recently using a time-dependent configuration-interaction singles approach [57], and the coupled-cluster method [17]; time-independent calculations have been performed using several approaches [58][59][60] including a recent GTO-only R-matrix one [61].…”

Section: Photoionization Of H 2 Omentioning

confidence: 99%

Perturbative and nonperturbative photoionization of H2 and H2O using the molecular R<

et al. 2020

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The ab initio R-matrix with time method has recently been extended to allow simulation of fully nonperturbative multielectron processes in molecules driven by ultrashort arbitrarily polarized strong laser fields. Here we demonstrate the accuracy and capabilities of the current implementation of the method for two targets: We study single-photon and multiphoton ionization of H 2 and one-photon and strong-field ionization of H 2 O and compare the results to available experimental and theoretical data as well as our own time-independent R-matrix calculations. We obtain a highly accurate description of total and state-to-state single-photon ionization of H 2 O and, using a simplified coupled-channel model, we show that state coupling is essential to obtain qualitatively correct results and that its importance as a function of laser intensity changes. We find that electron correlation plays a more important role at low intensities (up to approximately 50 TW/cm 2).

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Section: Photoionization Of H 2 Omentioning

confidence: 99%

Perturbative and nonperturbative photoionization of H2 and H2O using the molecular R<

et al. 2020

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“…For such a case, one can transform the problem to a rotating frame in which the Hamiltonian is time-indenpendent. The recent papers by Galstyan et al [128,129] are perhaps the closest to the approach developed by us in Refs. 110-114. In this section we discuss a useful non-local separable potential with the purpose of applications for atoms, but most importantly for large molecules.…”

Section: And References Therein)mentioning

confidence: 84%

“…Recently, it turned out to be extremely useful in modelling HHG and ATI in molecular dimers, trimers and quadrimers [116][117][118][119][120]. Other uses of separable potentials in the literature are discussed in [121][122][123][124][125][126][127][128][129][130][131][132][133][134][135].…”

Section: History Of the Sfamentioning

confidence: 99%

“…In 2D the situation is more complex due to the logarithmic divergences (see [343] and references therein). One should stress, however, that the use of separable potentials has a long history in strong-field physics [121][122][123][124][125][126][127][128][129][130][131][132][133][134][135]. Many of these papers deal with zero-range models, some with general separable potentials, but typically using laser fields of constant strength and circular polarization.…”

Section: Appendix C Model Atom and Moleculementioning

confidence: 99%

“…For such a case, one can transform the problem to a rotating frame in which the Hamiltonian is time-independent. The recent papers by Galstyan et al [134,135] are perhaps the closest to the approach developed by us in [116][117][118][119][120].…”

Section: Appendix C Model Atom and Moleculementioning

confidence: 99%

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Symphony on strong field approximation

et al. 2019

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In the last three decades, we have witnessed incredible advances in laser technology and in the understanding of nonlinear laser-matter interactions, crowned recently by the award of the Nobel prize to Gérard Mourou and Donna Strickland [1,2]. It is now routinely possible to produce few-cycle femtosecond (1 fs = 10 −15 s) laser pulses in the visible and mid-infrared regimes [3,4]. By focusing such ultrashort laser pulses on gas or solid targets, possibly in a presence of nano-structures [5], the targets are subjected to an ultra-intense electric field, with peak field strengths approaching the binding field inside the atoms themselves. Such fields permit the exploration of the interaction between strong electromagnetic coherent radiation and an atomic or molecular system with unprecedented spatial and temporal resolution [6]. On one hand, HHG nowadays can be used to generate attosecond pulses in the extreme ultraviolet [7,8], or even in the soft X-ray regime [9]. Such pulses themselves may be used for dynamical spectroscopy of matter; despite carrying modest pulse energies, they exhibit excellent coherence properties [10,11]. Combined with femtosecond pulses they can also be used to extract information about the laser pulse electric field itself [12]. HHG sources therefore offer an important alternative to other sources of XUV and X-ray radiation: synchrotrons, free electron lasers, X-ray lasers, and laser plasma sources. Moreover, HHG pulses can provide information about the structure of the target atom, molecule or solid [13][14][15]. Of course, to decode such information from a highly nonlinear HHG signal is a challenge, and that is why a possibly perfect, and possibly "as analytical as possible" theoretical understanding of these processes is in high demand. Here is the first instance where SFA offers its basic services.Since electronic motion is governed by the waveform of the laser electric field, an important quantity to describe the electric field shape is the so-called absolute phase or carrier-envelope phase (CEP). Control over the CEP is paramount for extracting information about electron dynamics, and to retrieve structural information from atoms and molecules [13,16,17]. For instance, in HHG an electron is liberated from an atom or molecule through ionization, which occurs close to the maximum of the electric field. Within the oscillating field, the electron can thus accelerate along oscillating trajectories, which may result in recollision with the parent ion, roughly when the laser field approaches a zero value. Control over the CEP is particularly important for HHG, when targets are driven by laser pulses comprising only one or two optical cycles. In that situation the CEP determines the relevant electron trajectories, i.e. the CEP determines whether emission results in a single or in multiple attosecond bursts of radiation [16,18].The influence of the CEP on electron emission is also extremely important. It was demonstrated for instance in an anti-correlation experiment, in which the number of AT...

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Separable Potentials Model for Atoms and Molecules in Strong Ultrashort Laser Pulses

Popov

Galstyan

Piraux

et al. 2019

Springer Series in Chemical Physics

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Ionisation of H 2 O by a strong ultrashort XUV pulse: a model within the single active electron approximation

Cited by 3 publications

References 22 publications

Perturbative and nonperturbative photoionization of H2 and H2O using the molecular R<

Perturbative and nonperturbative photoionization of H2 and H2O using the molecular R<

Symphony on strong field approximation

Separable Potentials Model for Atoms and Molecules in Strong Ultrashort Laser Pulses

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