Measurements of absolute Ar 3<i>s</i>photoionization cross sections

Möbus, B.; Magel, B.; Schartner, K.‐H.; Langer, Burkhard; Becker, Uwe; Wildberger, M.; Schmoranzer, H.

doi:10.1103/physreva.47.3888

Cited by 45 publications

(50 citation statements)

References 27 publications

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“…To demonstrate the accuracy of the method for an isolated atom, the total photoionization cross section and the partial 3s and 3p cross sections of Ar are presented in Fig. 2a and compared with available experiments [21,22]. As seen, our TDLDA total and 3s cross sections are in excellent agreement with experimental results and the positions of the 3s and 3p Cooper minima at, respectively, 42…”

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confidence: 74%

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Time Delay in the Recoiling Valence Photoemission of Ar Endohedrally Confined inC60

2013

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The effects of confinement and electron correlations on the relative time delay between the 3s and 3p photoemissions of Ar confined endohedrally in C60 are investigated using the time dependent local density approximation -a method that is also found to mostly agree with recent time delay measurements between the 3s and 3p subshells in atomic Ar. At energies in the neighborhood of 3p Cooper minimum, correlations with C60 electrons are found to induce opposite temporal effects in the emission of Ar 3p hybridized symmetrically versus that of Ar 3p hybridized antisymmetrically with C60. A recoil-type interaction model mediated by the confinement is found to best describe the phenomenon.PACS numbers: 32.80. Fb,With the tremendous advancement in technology for generating attosecond (as) isolated pulses as well as attosecond pulse trains, it becomes possible to study fundamental phenomena of light-matter interaction with unprecedented precision on an as timescale [1][2][3]. In particular, the relative time delay between the photoelectrons from different subshells on as timescale, a subject of intense recent activities, is expected to probe important aspects of electron correlations that predominantly influence the photoelectron. Pump-probe experiments have been performed to measure the relative delay in the photoemission processes, where extreme ultra-violet (XUV) pulses are used to remove an electron from a particular subshell and subsequently a weak infrared (IR) pulse accesses the temporal information of the emission event [4].Streaking measurements were carried out to probe photoemission from the valence and the conduction band in single-crystalline magnesium [5] and tungsten [6]. A streaking technique was also employed to measure the relative delay of approximately 21±5 as between the 2s and 2p subshells of atomic Ne at 106 eV photon energy [7]. Despite several theoretical attempts [8][9][10][11][12][13][14] to explain this measured delay in Ne, only about a half of the delay could be reproduced, keeping the time delay in Ne photoemissions still an open problem. Recently, the relative delay between the 3s and 3p subshells in Ar is measured at three photon energies by interferometric technique using attosecond pulses [15,16]. Theoretical methods (e.g. time-dependent nonperturbative method [8], diagrammatic many-body perturbation theory [13], Random phase approximation with exchange (RPAE) [14,16], and multi-configurational Hartree-Fock (MCHF) [17]) have been employed to investigate this relative delay in Ar, although agreements between theory and experiment is rather inconclusive. A ubiquitous understanding in all these studies is the dominant influence of electron correlations to determine the time behavior of outgoing electrons. Thus, it is fair to expect that the process near a Cooper minimum or a resonance will be particularly nuanced.It is therefore of spontaneous interest to extend the study to test the effect of correlations on the temporal photoresponse of atoms in material confinements. A brilliant natura...

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confidence: 74%

“…2a) also automatically implies the accuracy of our TDLDA 3p result. [21] and total [22]. For 3s the computed cross section is scaled to reproduce the measurement at the Cooper minimum.…”

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confidence: 99%

Time Delay in the Recoiling Valence Photoemission of Ar Endohedrally Confined inC60

2013

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“…[9], experimentally located at about 43 eV, is also located at higher photon energies in our calculations so that it does not affect the computed delays. We should also note that, above 39 eV, many more resonances could affect τ α W , corresponding to shake-up electrons in higher orbitals, even though they seem to be less important as far as the cross section is concerned [60].…”

Section: Application To Photoionization Delay Measurementsmentioning

confidence: 98%

Multiconfigurational Hartree-Fock close-coupling ansatz: Application to the argon photoionization cross section and delays

et al. 2013

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We present a robust, ab initio method for addressing atom-light interactions and apply it to photoionization of argon. We use a close-coupling ansatz constructed on a multiconfigurational Hartree-Fock description of localized states and B-spline expansions of the electron radial wave functions. In this implementation, the general many-electron problem can be tackled thanks to the use of the ATSP2K libraries [C. Froese Fischer et al., Comput. Phys. Commun. 176, 559 (2007)]. In the present contribution, we combine this method with exterior complex scaling, thereby allowing for the computation of the complex partial amplitudes that encode the whole dynamics of the photoionization process. The method is validated on the 3s3p 6 np series of resonances converging to the 3s extraction. Then, it is used for computing the energy dependent differential atomic delay between 3p and 3s photoemission, and agreement is found with the measurements of Guénot et al. [ Phys. Rev. A 85, 053424 (2012)]. The effect of the presence of resonances in the one-photon spectrum on photoionization delay measurements is studied.

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“…4 We can infer further information on the composition of the clusters we probe from the photoelectron spectra. A comparison of the area of Ne 2s and Ar 3s photoelectron lines, normalized by the respective cross sections, 21 gives an approximate measure of the relative Ar content, and for the pure Ar clusters at the higher expansion temperature the bulk/surface ratio gives an approximate measure of the cluster size. 22 For the spectrum shown in Figure 2, these analyses give an Ar fraction of 0.48(5) and a mean Ar cluster size of 100 (20) atoms.…”

Section: Discussionmentioning

confidence: 99%