Multiphoton ionization cross sections of neon and argon

McKenna, Claire; Hart, H. W. van der

doi:10.1088/0953-4075/37/2/013

Cited by 35 publications

(18 citation statements)

References 23 publications

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“…To understand the observed nonperturbative laser-power dependence in the high-frequency regime of EUV FEL, we have performed in the present study a numerical simulation of the time-dependent ionization probability by solving the timedependent Schrödinger equation for a light-coupled threelevel atom modeling the resonance two-photon ionization of atoms, assuming single-mode FEL pulses. A nonperturbative time-independent approach such as the Floquet approach [19][20][21][22][23] may also be used to rationalize the deviation from the power law, but it is not suitable for describing nonstational dynamical Rabi oscillations that occur within short laser pulses.…”

Section: Introductionmentioning

confidence: 99%

Suppression of ionization probability due to Rabi oscillations in the resonance two-photon ionization of He by EUV free-electron lasers

et al. 2011

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The two-photon resonance ionization probability of atoms in strong extreme-ultraviolet free-electron laser (EUV FEL) pulses has been investigated by the model of time-dependent wave packet propagation of a lightcoupled multilevel atom. Under the simulation within the model assuming single-mode FEL pulses, the ionization probability P ion has shown characteristic dependences on the scaled coupling parameter U gi between two levels of the ground (g) and intermediate (i) resonance states, namely, P ion ∝ (U gi ) n , with n being equal to ∼2, less than 1, and ∼1 for the small, medium, and large U gi regimes, respectively. This power dependence of the ionization probability has been interpreted due to Rabi oscillations between g and i states. To compare with recent experimental results on the same condition, the multimode nature of self-amplitude spontaneous emission (SASE) FEL pulses has been managed in the simulation. Then, the recent experimental laser-power dependence of the two-photon resonance ionization of He [Sato et al., J. Phys. B 44, 161001 (2011)] has been well described by that for the large U gi regime of the simulation, i.e., n ∼ 1. Thus, the observed linear laser-power dependence has been rationalized as being caused by the strong Rabi oscillations between the (2p)-(1s) states.

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Section: Introductionmentioning

confidence: 99%

Suppression of ionization probability due to Rabi oscillations in the resonance two-photon ionization of He by EUV free-electron lasers

et al. 2011

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“…In this case, Eqs. (2) can be easily solved and using the atomic data, σ 0 ≈ 273 Mb [13], σ 1 ≈ 0.18 Mb [14], and σ 2 ≈ 2 × 10 −49 cm 4 s [18], one obtains that in the Ne 1000 cluster after the pulse 991 atoms will be excited and only 3 will be ionized by a two-photon ionization. Since, as we saw, the ICD process is very efficient, one would expect that every pair of Ne * (2p −1 3s) will undergo ICD producing about 495 neon ions.…”

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Ultrafast Interatomic Electronic Decay in Multiply Excited Clusters

et al. 2010

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An ultrafast mechanism belonging to the family of interatomic Coulombic decay (ICD) phenomena is proposed. When two excited species are present, an ultrafast energy transfer can take place bringing one of them to its ground state and ionizing the other one. It is shown that if large homoatomic clusters are exposed to an ultrashort and intense laser pulse whose photon energy is in resonance with an excitation transition of the cluster constituents, the large majority of ions will be produced by this ICD mechanism rather than by two-photon ionization. A related collective-ICD process that is operative in heteroatomic systems is also discussed.PACS numbers: 31.70. Hq, 32.80.Rm, 32.80.Wr The rapid development during the last decades of very intense light sources with extreme short pulse duration opened a new era in the study of radiation-matter interaction. Studying the interaction of intense fields with matter brought to the discovery of a whole plethora of new physical phenomena, like high-harmonic generation, above-threshold ionization, or tunneling ionization, to name only a few. In the same time, the progress in generating extremely short pulses gave the scientific community a powerful tool to monitor and control the electron dynamics in atomic and molecular systems and to study processes that take place on a time scale in which the electronic motion is still disentangled from the slower nuclear dynamics (for recent reviews see, e.g., Refs. [1, 2]). A number of free-electron lasers are in operation today providing extremely bright, coherent, and ultrashort pulses in the VUV regime. Exposed to such highly intense pulses, atomic and molecular systems will absorb a large amount of photons triggering various dynamical effects. In this letter we will restrict ourselves to situations where the single-photon energy in the pulse is not high enough to directly ionize the system. It is well known that even in this case the system can be ionized by a multiphoton ionization mechanism. The multiphoton ionization (MPI) results from the ability of quantum systems to absorb several and even many photons, whose individual energies are insufficient to ionize the system. The combined energy of the absorbed photons, though, suffices to eventually eject one or many electrons from the system. During the last decade the MPI has been intensively studied also in composite systems, like clusters, employing the new powerful laser sources (for a review see, e.g. Ref.[3]). However, little attention was paid to other mechanisms that can lead to a multiple ionization in an atomic or molecular cluster irradiated by an intense laser pulse.In this letter we aim at discussing a hitherto unrecognized mechanism for producing ionized species in homoatomic or homomolecular clusters exposed to an intense laser pulse, which in many cases can be by far One of the constituents of the system de-excites transferring the energy to the neighbor which uses it to emit its excited electron.the dominating one. For simplicity we will consider an atomic cluste...

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“…By applying R-matrix theory to this Floquet Hamiltonian, we obtain the energy and ionization rate of an atomic state in the presence of a laser field with a particular frequency and intensity. This approach has been applied with great success to a variety of processes and atoms, such as multiphoton ionization of Ne and Ar [7], two-photon double ionization of He [8], and detailed investigations of the resonance structure in multiphoton ionization in He at 390 nm [9].…”

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Two-Photon Detachment of Inner-Shell Electrons fromLi−

Hart

2005

Phys. Rev. Lett.

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We investigate two-photon detachment of an inner 1s electron from the 1s22s2 ground state of Li- using R-matrix Floquet theory. This detachment rate shows a noticeable structure due to shape resonances just above the lowest three doubly excited thresholds of Li. Two-photon detachment of one 1s electron is about twice as likely as two-photon detachment of (at least) one 2s electron. Two-photon detachment of one 1s electron may be observable experimentally through the detection of electrons with kinetic energies between 45 and 65 eV.

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Multiphoton ionization cross sections of neon and argon

Cited by 35 publications

References 23 publications

Suppression of ionization probability due to Rabi oscillations in the resonance two-photon ionization of He by EUV free-electron lasers

Suppression of ionization probability due to Rabi oscillations in the resonance two-photon ionization of He by EUV free-electron lasers

Ultrafast Interatomic Electronic Decay in Multiply Excited Clusters

Two-Photon Detachment of Inner-Shell Electrons fromLi−

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