Interaction of molecular nitrogen with free-electron-laser radiation

Banks, H. I. B.; Little, Duncan A.; Tennyson, Jonathan; Emmanouilidou, A.

doi:10.1039/c7cp02345f

Cited by 20 publications

(32 citation statements)

References 51 publications

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“…In this work, we compute single-photon ionisation crosssections and Auger rates for xenon, by adapting to atoms the formalism we have previously developed for diatomic molecules [21]. In the non-relativistic regime, this formalism is general and is applicable to complex multi-electron atoms where the orbital wave functions are accurately described by many l quantum numbers.…”

Section: Discussionmentioning

confidence: 99%

“…We assume that the Auger transition is a two-electron process, with H I being the electron-electron Coulomb repulsion term. We adapt to atoms the derivation used in our previous work for molecules [21]. We then find that the Auger rate involving two valence orbitals a and b, an inner-shell orbital c, and a continuum orbital with quantum numbers l, m is given by…”

Section: Auger Decaymentioning

confidence: 99%

“…To obtain the ion yields and the pathways underlying the formation of each ion state, we compute the single-photon ionisation cross sections and Auger decay rates for all energetically allowed transitions. We do so by adapting to atoms the formalism that we have previously developed for diatomic molecules [21]. Our formalism is general.…”

Section: Introductionmentioning

confidence: 99%

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Auger cascades leading to higher charged states in xenon driven by an X-ray free-electron-laser pulse

2020

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We study the interaction of xenon with an 850 eV photon energy FEL pulse. We compute singlephoton ionisation cross sections and Auger rates by adopting to atoms a formalism we previously developed for diatomic molecules. In this formulation, a bound orbital is expressed as a sum of wave functions each corresponding to a different l quantum number. In contrast, in previous formulations only one l quantum number is associated with a bound orbital. As a result, in the non-relativistic regime, the description of the bound states is more accurate in our computations. Employing a Monte-Carlo technique, we find that our results for the ion state yields of xenon compare well with experimental results. Moreover, we find that when xenon is driven by two FEL pulses of the same energy but different pulse duration, higher-charged states are produced in the case of the longer duration and less intense laser pulse. An analysis of the ionization pathways reveals that less single-photon absorptions underlie the formation of each higher-charged state for the longer duration pulse compared to the shorter one. We find that the reason for the formation of higher-charged states for the longer duration pulse is the prevalence of Auger cascades.

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Section: Discussionmentioning

confidence: 99%

Section: Auger Decaymentioning

confidence: 99%

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Auger cascades leading to higher charged states in xenon driven by an X-ray free-electron-laser pulse

2020

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“…The operator H I describes the Coulomb repulsion between the two electrons involved in the Auger transition. The derivation of the Auger decay rate for molecules in our previous work [37] involves bound molecular orbitals which are expressed as a sum of l, m quantum numbers. In contrast, our previous work regarding the interaction of free-electron laser pulses with Ar [4,22] involves bound orbitals, where only one l quantum number is associated with each orbital.…”

Section: Auger Decaymentioning

confidence: 99%

Sequential single-photon and direct two-photon absorption processes for Xe interacting with attosecond XUV pulses

et al. 2020

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We investigate the interaction of Xe with isolated attosecond XUV pulses. Specifically, we calculate the ion yields and determine the pathways leading to the formation of ionic charged states up to Xe 5+. To do so, in our formulation we account for single-photon absorption, sequential multiphoton absorption, direct two-photon absorption, single and double Auger decays, and shake-off. We compare our results for the ion yields and for ion yield ratios with recent experimental results obtained for 93 and 115 eV attosecond XUV pulses. In particular, we investigate the role that a sequence of two single-photon ionization processes plays in the formation of Xe 4+. We find that each one of these two processes ionizes a core electron and thus leads to the formation of a double core-hole state. Remarkably, we find that the formation of Xe 5+ involves a direct two-photon absorption process and the absorption of a total of three photons.

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“…The dissociation of the molecule is taken into account mostly in a phenomenological way through additional terms in the rate equations employed to compute the resulting atomic ion yields. 10 In this work, we compute potential energy curves of singly and doubly ionized molecular nitrogen. This will allow future studies to explicitly account for the nuclear motion when a molecule interacts with an FEL-pulse.…”

Section: Introductionmentioning

confidence: 99%

Potential Energy Curves of Molecular Nitrogen for Singly and Doubly Ionized States with Core and Valence Holes

Bhattacharya

Shamasundar²,

Emmanouilidou³

2021

Preprint

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Our manuscript, presents the computation of potential energy curves of all possible singly and doubly ionized states of molecular nitrogen. Accurate representation of the potential energy curves of ionized states of N2 is essential to explicitly treat coupled electron-nuclear dynamics. In this work, we compute the potential energy curves of the valence as well as the core and inner valence singly and doubly ionized states of N2. These curves pave way to study the interplay between photoionization and Auger spectra when molecular nitrogen interacts with free electron lasers.Computation of inner valence or core ionized potential energy curve is not trivial due to the well-known problem of variational collapse of the wavefunction to the lowest energy state. We circumvent this problem by implementing a two-step optimization scheme within the multi-configurational self-consistent field approach. Such a two-step optimization scheme has been previously implemented to compute potential energy curves of core ionized states of di-atomic molecules with one hole. Herein, we show the general applicability of this two-step optimization method by computing potential energy curves of both singly and doubly ionized states of N2 with valence and core holes. Calculation of potential energy curves for core ionized polyatomic systems are scarce. Moreover, our approach is system independent and can be easily extended to calculate multiple-core ionized states. To the best of our knowledge, this is the first calculation of potential energy curves for doubly ionized states of a diatomic molecule with two core (or inner valence) holes.

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Interaction of molecular nitrogen with free-electron-laser radiation

Cited by 20 publications

References 51 publications

Auger cascades leading to higher charged states in xenon driven by an X-ray free-electron-laser pulse

Auger cascades leading to higher charged states in xenon driven by an X-ray free-electron-laser pulse

Sequential single-photon and direct two-photon absorption processes for Xe interacting with attosecond XUV pulses

Potential Energy Curves of Molecular Nitrogen for Singly and Doubly Ionized States with Core and Valence Holes

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