Observation of oscillations between degenerate bound-state configurations in rapidly autoionizing two-electron atoms

Campbell, M. B.; Bensky, Thomas J.; Jones, Robert R.

doi:10.1103/physreva.57.4616

Cited by 20 publications

(16 citation statements)

References 18 publications

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“…At the temporal resolution of the experiment, high-frequency Ramsey fringes corresponding to the excitation frequencies of each AIS are averaged out and the low-frequency components of the evolution of the coherent superposition dominate the trace 22 . Contributions from modulations in the excitation process due to the two interfering wave packets are not to be excluded 23,24 . Fourier transform (FT) of the traces reveals frequency differences of the excited states (Fig.…”

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Extreme-ultraviolet pump–probe studies of one-femtosecond-scale electron dynamics

et al. 2011

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Ultrafast-dynamics studies and femtosecond-pulse metrology both rely on the nonlinear processes induced solely by an incident light pulse. Extending these approaches to the extreme-ultraviolet (XUV) spectral region would open up a new route to attosecond-scale dynamics. However, this has been hindered by the limited intensities available in coherent XUV continua. In the present work, we realized conditions at which simultaneous ejection of two bound electrons by two-XUVphoton absorption becomes more efficient than their removal one-by-one. In this regime we have succeeded in tracing atomic coherences evolving at the 1-fs scale with simultaneous determination of the average XUV-pulse duration. The rich and dense structure of the autoionizing manifold demonstrates the applicability of the approach to complex systems. This initiates the era of XUV-pump-XUV-probe experiments at the boundary between femto-and attosecond scales.A large variety of ultrafast phenomena, including electronic motion in atoms, molecules, condensed matter and plasmas, dynamic electron-electron correlations, charge migration, ultrafast dissociation and reaction processes, occur on the few-femtosecond to attosecond temporal scale. Attosecond (as) pulses 1 provide access to these temporal regimes in different states of matter [2][3][4][5][6] . Nonlinear (NL) XUV processes constitute the ideal tool for the study of such dynamics. Attosecond pulse trains 7-9 have reached intensities sufficient to induce two-XUV-photon processes [10][11][12][13][14] . However, isolated attosecond pulses, requisite for XUV-pump-XUV-probe experiments, have not yet attained the required parameters for an observable two-XUV-photon process. As a consequence, attosecond pulse metrology and time-domain applications have been widely based on infrared (IR)-XUV cross-correlation approaches, which entail assumptions for the analysis 15 .The present work succeeds for the first time in observing two-XUV-photon processes induced by energetic XUV continua, in part temporally confined in isolated pulses with durations on the order of 1 fs. These processes are in turn exploited in XUVpump-XUV-probe ultrafast evolving atomic coherences, as well as in determining the duration of the XUV bursts. A structured part of the single continuum of the xenon atom is excited by the first pulse, forming an electronic wave packet that undergoes rapid and complex motion before it decays. This evolution can be traced, thanks to the XUV parameters reached, at which a second pulse ejects a second electron before the first one leaves the atom carrying with it all the information on the temporal evolution of the system (coherence decay). Unconventionally, the two electrons leave the atom together and, thus, the doubly ionized Xe yield as a function of the delay between the two pulses carries the fingerprint of the wave packet motion and the XUV pulse duration. As the pulse duration and the decay The intense XUV radiation is generated by frequency upconversion of many-cycle high-peak-power laser fields...

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Extreme-ultraviolet pump–probe studies of one-femtosecond-scale electron dynamics

et al. 2011

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“…Dynamics of wave packets in this two-electron system have also been studied [15]. Some effects of oscillating bound configurations on wave packet behavior have been observed [16]. Quantum measurement studies have also been performed using a perturbative ICE [17].…”

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Observation of a Nondecaying Wave Packet in a Two-Electron Atom

Chen

Yeazell

1998

Phys. Rev. Lett.

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We excite and manipulate wave packets in the Rydberg states of atomic calcium. The manipulation is via the electron-electron correlations between a core electron and the Rydberg electron and mediated by a strong excitation of the core transition. Striking changes in the wave packet are observed particularly when the Rabi oscillations of the core transition are synchronized with the natural, classical oscillation frequency of the Rydberg wave packet. In that case, the wave packet is shaped into a form that inhibits decay or autoionization as demonstrated by a coherent probe of the resulting wave packet. This work impacts on both coherent control and quantum measurement studies. [S0031-9007(98)08062-4] PACS numbers: 32.80.Qk, 32.80.Dz, 32.80.Rm We have observed the formation of a nondecaying wave packet. A Rydberg electronic wave packet was excited in atomic calcium and further manipulated via a strong core excitation into this nondecaying form.The creation, control, and measurement of wave packets are central topics in a broad range of research areas. Specially designed wave packets have been proposed (and to a lesser extent implemented) to control key processes in atomic [1], molecular [2], and solid state systems [3]. Such wave packets also play a significant role in understanding measurement aspects of quantum mechanics [4,5].Wave packets are nonstationary states that are phased superpositions of highly excited atomic eigenstates. Among the simplest of these to excite is the radially localized wave packet. These are routinely created by short pulse excitation in a single-electron atom that produces a superposition of states with different principal quantum numbers (n). A typical distribution is Gaussian with a FWHM of seven states centered on an average n ofn 50. On a short time scale, these wave packets demonstrate nearly classical behavior [6]. That is, the radial wave packet oscillates at the classical period, t cl 2pn 3 , between the inner and outer turning point of the classical electron's orbit. At longer times, quantum mechanics plays a distinct role and the wave packet disperses and displays a regular interference pattern that contains both fractional [7] and full revivals [8] of the wave packet. Recently, radially localized wave packets in two-electron systems have been excited that demonstrate nearly identical temporal behavior [9].In this paper, we control the behavior of a radially localized wave packet in a two-electron system by driving the remaining, correlated valence electron. One of the valence electrons is excited by a short pulse to a radially localized wave packet state. The remaining core electron is driven so that it oscillates between its ground state and its first excited state. The states of this core electron are much like the states of the singly ionized atom or like that of a single electron atom so that this type of excitation is described as an isolated core excitation (ICE) [10]. When the core electron is in the ground state the two-electron system is bound. In contrast, if th...

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“…The evolution of wave packets is highly dependent on the spacing between states, making Stark states an excellent system in which to study temporal dynamics, since the evolution of the wave packets can be controlled by simply changing the size of the applied electric field. The use of Rydberg wave packets in the study of doubly excited atoms has been shown to be a useful tool for studying the dynamical interaction between the two excited electrons [10][11][12][13][14][15][16][17][18][19][20]. The use of applied electric fields to control the evolution of the two electron wave packets provides a sensitive tool in the study of the interelectron interaction.…”

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Electric Field Controlled, Pulsed Autoionization in Two Electron Wave Packets

Story

Ereifej

2001

Phys. Rev. Lett.

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In this paper, control of the evolution of a two electron wave packet through the application of a static electric field is demonstrated. Specifically, application of a small electric field is used to produce pulsed autoionization events, the timing of which can be controlled on a picosecond time scale. The technique is demonstrated by exciting calcium atoms using a short-pulsed laser to the 4p(3/2)19d doubly excited state, which is energy degenerate with the 4p(1/2)nk stark states. Evolution of the resultant wave packet is monitored through the application of a second short laser pulse, which stimulates the atoms to emit a photon producing singly excited Rydberg states which are detected using field ionization.

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Observation of oscillations between degenerate bound-state configurations in rapidly autoionizing two-electron atoms

Cited by 20 publications

References 18 publications

Extreme-ultraviolet pump–probe studies of one-femtosecond-scale electron dynamics

Extreme-ultraviolet pump–probe studies of one-femtosecond-scale electron dynamics

Observation of a Nondecaying Wave Packet in a Two-Electron Atom

Electric Field Controlled, Pulsed Autoionization in Two Electron Wave Packets

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