Observation of New Rydberg Series and Resonances in Doubly Excited Helium at Ultrahigh Resolution

Schulz, K.; Kaindl, G.; Domke, M.; Bozek, John D.; Heimann, Philip; Schlachter, A. S.; Rost, Jan-Michael

doi:10.1103/physrevlett.77.3086

Cited by 141 publications

(111 citation statements)

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“…The magnitude of V CI determines the lifetimes of the transiently bound states. In our case, these range between 17 fs for the 2s2p (sp 2,2 ) 18 and several hundreds of femtoseconds for some higher-lying sp 2,n+ states 15 . As these lifetimes are that short, with energy-level spacings on the order of several eV, the coupling dynamics between the states in external fields must be measured using ultrashort pulses.…”

mentioning

confidence: 72%

“…The VIS stray light was removed with a pair of 200 nm thin aluminium metal filters. The spectrometer calibration was obtained by identifying the observed sp 2,n+ two-electron resonance lines in helium and using tabulated experimental values of high-precision synchrotron measurements 34,15 . The spectral resolution (σ = 20 meV Gaussian standard deviation) near 60 eV resulted from a fit of the 2s2p resonance line.…”

Section: Methodsmentioning

confidence: 99%

“…The approximate time-dependent wave function |(t)exp(- 2s2p /2 t)|2s2p+a exp(- sp23+ /2 t)exp (-iυ(t))|sp 2,3+  is characterized by the relative phase υ(t) and amplitude a of the two contributing states 2s2p and sp 2,3+ . The states' slow amplitude decay is given by their respective natural decay width , accessible from static spectroscopy 15 at the resonance positions  2s2p ,  sp23+ . The relative phase υ(t) by contrast is not accessible in traditional spectroscopy.…”

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confidence: 99%

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Reconstruction and control of a time-dependent two-electron wave packet

Ott

Kaldun

Argenti

et al. 2014

Nature

265

218

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Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: The concerted motion of two or more bound electrons governs atomic 1 and molecular 2,3 non-equilibrium processes and chemical reactions. It is thus a long-standing scientific dream to measure and control the dynamics of two bound and correlated electrons in the quantum regime. At least two active electrons and a nucleus are required to address such quantum three-body problem 4 for which analytical solutions do not exist, a condition that is met in the helium atom. While attosecond dynamics were previously observed for singleactive electron/hole cases 5-7 , such time-resolved observation of two-electron motion thus far remained an unaccomplished challenge. Here, we measure a 1.2-femtosecond quantum beat among low-lying doubly-excited states in helium and use it to reconstruct a correlated two-electron wave packet. Our experimental method combines attosecond transientabsorption spectroscopy 5,7-9 at unprecedented high spectral resolution (20 meV s.d. near 60 eV) with an intensity-tuneable visible laser field to couple 10-12 the quantum states from the weak-field to the strong-coupling regime. Employing the Fano resonance as a phasesensitive quantum interferometer 13 , we demonstrate the coherent control of two correlated electrons, which form the basis of most covalent molecular bonds in nature. As we show, such multi-dimensional spectroscopy experiments provide benchmark data for testing fundamental few-body quantum-dynamics theory. They also light a route for site-specific measurement and control of metastable electronic transition states that are at the heart of fundamental reactions in chemistry and biology.Electrons are bound to atoms and molecules by the Coulomb force of the nuclei. Moving between atoms, they form the basis of the molecular bond. The same Coulomb force, however, acts repulsively between the electrons. This electron-electron interaction represents a major challenge in the understanding and modelling of atomic and molecular states, their structure and in particular their dynamics 2,3,14 . Here, we focus on the 1 P sp 2,n+ series 15 of doubly-excited states in helium below the N = 2 ionization threshold. They are excited by a single-photon transition from the 1 S 1s 2 ground state by the promotion of both electrons to at least principal quantum number n = 2. The states autoionize due to electron-electron interaction and their spectroscopic signature manifests as asymmetric non-Lorentzian line shapes. The latter were first observed in the 1930s 16 and attributed 17 , by Ugo Fano, to the quantum interference of bound states with the continuum to which they are coupled (Fig. 1c,d). The coupling is described by the configuration interaction V CI with the single-ionization continuum |1s,p, where one electron is in the 1s ground state and the other one is in the continuum with kinetic energy . The magnitude of V CI determines the lifetimes of the transiently bound states. In our case,...

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confidence: 72%

Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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Reconstruction and control of a time-dependent two-electron wave packet

Ott

Kaldun

Argenti

et al. 2014

Nature

265

218

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“…Simultaneous excitation of all three electrons can create hollow lithium states of the type nᐉn 0 ᐉ 0 n 00 ᐉ 00 with n $ 2 [1-5]. A calculation of some low-lying hollow lithium states in hyperspherical coordinates has been recently carried out [6] as a step towards the development of a classification scheme for triply excited states, analogous to the ͑K, T͒ A radial and angular correlation quantum numbers [7,8] used to describe the doubly excited states of helium [9]. For future understanding an important question is whether hollow lithium states exist which can be regarded as heliumlike doubly excited Li 1 terms plus a running outer electron or is the configuration mixing so great that Rydberg states of this type are absent?…”

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confidence: 99%

Experimental Observation and Theoretical Calculations of Rydberg Series in Hollow Lithium Atomic States

et al. 1997

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Several extended Rydberg series have been experimentally identified in triply excited states of hollow lithium, by use of electron spectrometry and synchrotron radiation at the Advanced Light Source. Energies, partial cross sections, and quantum defects have also been calculated using the R-matrix approximation. Our results show that the two inner electrons stay in a core-excited state of given symmetry while the behavior of the third electron is mostly governed by the nuclear potential screened by the two inner electrons. [S0031-9007(97)03826-X] PACS numbers: 32.80. Hd, 32.80.Fb, 32.80.Rm We present here the first experimental evidence demonstrating the existence of several extended Rydberg series in the hollow triply excited states of lithium. These new results, obtained using electron spectrometry and synchrotron radiation, are supported by our theoretical calculations made using the R-matrix approximation. We also explain why these Rydberg series have not been observed previously.The inner shell (K, or 1s) in a hollow atomic or ionic state is empty. Simultaneous excitation of all three electrons can create hollow lithium states of the type nᐉn 0 ᐉ 0 n 00 ᐉ 00 with n $ 2 [1-5]. A calculation of some low-lying hollow lithium states in hyperspherical coordinates has been recently carried out [6] as a step towards the development of a classification scheme for triply excited states, analogous to the ͑K, T͒ A radial and angular correlation quantum numbers [7,8] used to describe the doubly excited states of helium [9]. For future understanding an important question is whether hollow lithium states exist which can be regarded as heliumlike doubly excited Li 1 terms plus a running outer electron or is the configuration mixing so great that Rydberg states of this type are absent? An earlier experiment [3] measuring the yield of Li 1 ions by photoion spectrometry did not reveal such series features. In fact, the authors specifically stated [3] "that the most striking aspect of the ion spectrum is the complete absence of any identifiable Rydberg series structure." Later measurements taking advantage of the final-state selectivity of photoelectron spectroscopy [4,5] suggested, however, that some of the observed structures could be identified as first members of Rydberg series. But their effect on partial cross sections for photoionization into final Li 1 ionic states with one vacancy in the 1s shell was very weak and no higher terms of any series were observed.We have carried out new theoretical R-matrix calculations which predict the existence of eight Rydberg series between 150 and 160 eV, i.e., 1s 2 2s 2 S 1 hn ! ͓͑2s 2 1 S͒np͔ 2 P, ͓͑2s2p 3 P͒ns or nd͔ 2 P, ͓͑2p 2 3 P͒np͔ 2 P, ͓͑2p 2 1 D͒np͔ 2 P, ͓͑2s2p 1 P͒ns or nd͔ 2 P, and ͓͑2p 2 3 1 S͒np͔ 2 P. In Fig. 1, we show the calculated partial cross section for photoionization into the 1s2ᐉ final Li 1 FIG. 1. R-matrix calculation of partial cross section for photoionization of Li atoms into the ͑1s2ᐉ͒ 1,3 L final states of the Li 1 ion.

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“…The design resolving power (El AE) of the monochromator is 10 000, and the design flux at this resolving power is greater than 10 12 photons/second in the energy range 20-300 eV. Under certain circumstances the resolving power can be as high as 64000 (1 meV at 64 eV), albeit at significantly reduced flux [2]. This resolving power is a factor of 4 better than has ever been achieved in the soft X-ray region.…”

Section: Introductionmentioning

confidence: 81%

Ultra-High Resolution Atomic and Molecular Spectroscopy at the Advanced Light Source

Schlachter

Bozek

1997

Acta Phys. Pol. A

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Ultra-bright ultraviolet and soft X-ray beams produced at the Advanced Light Source are achieving world records in spectroscopic resolution. High-resolution spectroscopy in the 20 to 300 eV photon energy range has been applied to photoionization yield and photoemission measurements in atoms and molecules to reveal previously unseen resonance series in doubly--excited autoionizing states of helium, to analyze angular distributions in photoemission from doubly-excited states of helium and other rare gases, to reveal vibrational and ligand-field splitting of small molecules through photoionization, and, to examine photoemission from doubly-and triply-excited hollow lithium atomic states.

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Observation of New Rydberg Series and Resonances in Doubly Excited Helium at Ultrahigh Resolution

Cited by 141 publications

References 16 publications

Reconstruction and control of a time-dependent two-electron wave packet

Reconstruction and control of a time-dependent two-electron wave packet

Experimental Observation and Theoretical Calculations of Rydberg Series in Hollow Lithium Atomic States

Ultra-High Resolution Atomic and Molecular Spectroscopy at the Advanced Light Source

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