Resonance Effects in Photoemission Time Delays

Sabbar, Mazyar; Heuser, Sebastian; Boge, Robert; Lucchini, Matteo; Carette, Thomas; Lindroth, Eva; Gallmann, L.; Cirelli, Claudio; Keller, U.

doi:10.1103/physrevlett.115.133001

Cited by 101 publications

(93 citation statements)

References 37 publications

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“…This is again the consequence of a propagation-induced chirp of the electron wave packet in combination with an energy-dependent transmission probability, which shifts the center of the wave packet in time without any direct physically meaningful connection to the semiclassical motion of the electron [24].…”

Section: Discussionmentioning

confidence: 99%

Control of photoemission delay in resonant two-photon transitions

et al. 2017

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The photoelectron emission time delay τ associated with one-photon absorption, which coincides with half the Wigner delay τ W experienced by an electron scattered off the ionic potential, is a fundamental descriptor of the photoelectric effect. Although it is hard to access directly from experiment, it is possible to infer it from the time delay of two-photon transitions, τ (2) , measured with attosecond pump-probe schemes, provided that the contribution of the probe stage can be factored out. In the absence of resonances, τ can be expressed as the energy derivative of the one-photon ionization amplitude phase, τ = ∂ E arg D Eg , and, to a good approximation, τ = τ (2) − τ cc , where τ cc is associated with the dipole transition between Coulomb functions. Here we show that, in the presence of a resonance, the correspondence between τ and ∂ E arg D Eg is lost. Furthermore, while τ (2) can still be written as the energy derivative of the two-photon ionization amplitude phase,Eg , it does not have any scattering counterpart. Indeed, τ (2) can be much larger than the lifetime of an intermediate resonance in the two-photon process or more negative than the lower bound imposed on scattering delays by causality. Finally, we show that τ (2) is controlled by the frequency of the probe pulse, ω IR , so that by varying ω IR , it is possible to radically alter the photoelectron group delay.

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Section: Discussionmentioning

confidence: 99%

Control of photoemission delay in resonant two-photon transitions

et al. 2017

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“…The collection of the streaked spectra is called a spectrogram. So far such streaking experiments have been reported for atoms, molecules, and condensed matter in numerous experiments [5][6][7][8][9][10][11]. Despite these activities, what information on the structure or the photoionization dynamics of the target can be extracted from these experiments is still rather unclear.…”

Section: Introductionmentioning

confidence: 99%

Critical evaluation of attosecond time delays retrieved from photoelectron streaking measurements

2016

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A photoelectron streaking experiment which was conceived as a means to extract the electron wave packet of single-photon ionization has also been employed to retrieve time delays in the fundamental photoemission processes. The discrepancies between the time delays thus measured and those from many sophisticated theoretical calculations have generated a great deal of controversy in recent years. Here we present a careful examination of the methods that were used to retrieve the time delays and demonstrate the difficulty of achieving an accuracy of the retrieved time delays of a few to tens of attoseconds in typical streaking measurements. The difficulty owes more to the lower sensitivity of the streaking spectra to the phase of the photoionization transition dipole than to the spectral phase of the attosecond light pulse in the experiment. The retrieved time delay contains extra errors when the attochirp of the attosecond pulse is large so that the dipole phase becomes negligible compared to it.

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“…While the pulse duration of a typical few-cycle pulse is IR ≃ 5 fs (the period IR of an optical cycle for 800 nm radiation is IR = 2.7 fs), its oscillating field, controlled to within a small fraction of one radian, offers a convenient route to attosecond time resolution. The three different approaches utilized so far, linear momentum attosecond streaking with linearly polarized IR fields Drescher et al, 2001;Kienberger et al, 2004;Sansone et al, 2006;Cavalieri et al, 2007;Schultze et al, 2010;Sabbar et al, 2015), angular streaking ("attoclock"; Eckle et al, 2008a,b;Pfeiffer et al, 2011aPfeiffer et al, ,b, 2013 with circularly polarized IR fields, and the interferometric RABBIT technique (Paul et al, 2001;Toma and Muller, 2002;Mauritsson et al, 2005;Swoboda et al, 2010;Klünder et al, 2011;Guénot et al, 2012Guénot et al, , 2014Palatchi et al, 2014), have in common that the IR field probes the evolution during the emission, as implied by Eq. (2.18), without, however, necessarily performing a projective measurement which would lead to the "collapse of the wavepacket", i.e., to the reduction of the density operator.…”

Section: )mentioning

confidence: 99%

“…Guénot et al (2014) have reported on relative delays between argon, neon, and helium for photon energies between 31 eV and 37 eV employing RABBITT with an active stabilization of the interferometer. Sabbar et al (2015) performed streaking measurements of the relative delay between argon and neon in a photon energy region between 28 eV and 38 eV by using a gas mixture. RAB-BITT measurements for helium, neon, argon and krypton over a wider range of energies were also reported by Palatchi et al (2014).…”

Section: Time-resolved Photoionization Of Many-electron Atomsmentioning

confidence: 99%

Attosecond chronoscopy of photoemission

2015

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Recent advances in the generation of well characterized sub-femtosecond laser pulses have opened up unpredicted opportunities for the real-time observation of ultrafast electronic dynamics in matter. Such attosecond chronoscopy allows a novel look at a wide range of fundamental photophysical and photochemical processes in the time domain, including Auger and autoionization processes, photoemission from atoms, molecules, and surfaces, complementing conventional energy-domain spectroscopy. Attosecond chronoscopy raises fundamental conceptual and theoretical questions as which novel information becomes accessible and which dynamical processes can be controlled and steered. These questions are currently a matter of lively debate which we address in this review. We will focus on one prototypical case, the chronoscopy of the photoelectric effect by attosecond streaking. Is photoionization instantaneous or is there a finite response time of the electronic wavefunction to the photoabsorption event? Answers to this question turn out to be far more complex and multi-faceted than initially thought. They touch upon fundamental issues of time and time delay as observables in quantum theory. We review recent progress of our understanding of time-resolved photoemission from atoms, molecules, and solids. We will highlight the unresolved and open questions and we point to future directions aiming at the observation and control of electronic motion in more complex nanoscale structures and in condensed matter.

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Resonance Effects in Photoemission Time Delays

Cited by 101 publications

References 37 publications

Control of photoemission delay in resonant two-photon transitions

Control of photoemission delay in resonant two-photon transitions

Critical evaluation of attosecond time delays retrieved from photoelectron streaking measurements

Attosecond chronoscopy of photoemission

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