Time delay in molecular photoionization

Hockett, Paul; Frumker, E.; Villeneuve, D. M.; Corkum, P. B.

doi:10.1088/0953-4075/49/9/095602

Cited by 86 publications

(85 citation statements)

References 61 publications

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“…We observe variations of the phase in the X-state that is attributed to the presence of the shape resonance. Our results are in agreement with theoretical calculations based on single photon ionization [24][25][26].…”

Section: Introductionsupporting

confidence: 91%

“…, the experimental energetically resolved phase is shown in thin black curve, for each peak, the mean experimental phases and their corresponding error-bars (calculated over the indicated width) are shown with green lines for the X-state and with orange lines for the A-state. (c) Relative ionization time between the X and the A-states as a function of the harmonic order difference experimental measurement (black dots, see text for method) and the theoretical prediction for the X-state only from ePolyScat [24][25][26] (purple line). Figure 2(a) shows the experimental differential spectrogram obtained by angularly integrating the signal over the top side of the image and subtracting the signal obtained with XUV alone.…”

Section: Methodsmentioning

confidence: 99%

“…This experimental result can be compared with the one-photon matrix element calculation performed by Hockett et al [24,32] from ePolyScat suite codes [25,26,33]. In this calculation, the transition matrix elements of the X-state is calculated at the first order perturbation theory, for different polarization and using dipole and fixed nuclei approximations.…”

Section: Ionization To the X State Of Nitrogenmentioning

confidence: 99%

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High harmonic generation-2ω attosecond stereo-photoionization interferometry in N₂

et al. 2020

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We have investigated photoionization delays in N 2 by combining an extreme ultraviolet (XUV) attosecond pulse train generated by high harmonic generation (HHG) and a second harmonic femtosecond pulse with angularly resolved photoelectron spectroscopy. While photoionization delay measurements are usually performed by using a standard XUV-infrared scheme, here we show that the present approach allows us to separate electronic states that otherwise would overlap, thus avoiding the spectral congestion found in most molecules. We have found a relative delay between the X and A ionic molecular states as a function of the photon energy of up to 40 attoseconds, which is due to the presence of a shape resonance in the X channel. This approach can be applied to other small quantum systems with few active electronic states.

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Section: Introductionsupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Ionization To the X State Of Nitrogenmentioning

confidence: 99%

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High harmonic generation-2ω attosecond stereo-photoionization interferometry in N₂

et al. 2020

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“…The latter effect is especially strong for photoelectron emission close to the nodes of the photoelectron angular distributions where the probability of electron emission is low. Other recent work on photoionization time delays include the measurement and interpretation of attosecond laser-assisted delays from anisotropic molecular targets [32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Attosecond delays in laser-assisted photodetachment from closed-shell negative ions

Lindroth

Dahlström

2017

Phys. Rev. A

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We study laser-assisted photodetachment time delays by attosecond pulse trains from the closedshell negative ions F − and Cl − . We investigate the separability of the delay into two contributions: (i) the Wigner-like delay associated with one-photon ionization by the attosecond pulse train and (ii) the delay associated with exchange of an additional laser photon in the presence of the potential of the remaining target. Based on the asymptotic form of the wave packet, the latter term is expected to be negligible because the ion is neutralized leading to a vanishing laser-ion interaction with increasing electron-atom separation. While this asymptotic behavior is verified at high photoelectron energies, we also quantify sharp deviations at low photoelectron energies. Further, these low-energy delays are clearly different for the two studied anions indicating a breakdown of the universality of laser-ion induced delays. The fact that the short-range potential can induce a delay of as much as 50 as can have implications for the interpretation of delay measurements also in other systems that lack long-range potential.

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“…refs. [8,26,28,54]) for a large number of partial waves, and the concept has recently been demonstrated for the atomic case [47]; equivalently, one can consider the technique as a means of obtaining full angle-resolved Wigner delays [3,55].…”

Section: Extended Ar-rabbitmentioning

confidence: 99%

Angle-resolved RABBITT: theory and numerics

Hockett

2017

J. Phys. B: At. Mol. Opt. Phys.

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I. ABSTRACTAngle-resolved (AR) RABBIT measurements offer a high information content measurement scheme, due to the presence of multiple, interfering, ionization channels combined with a phase-sensitive observable in the form of angle and time-resolved photoelectron interferograms. In order to explore the characteristics and potentials of AR-RABBIT, a perturbative 2-photon model is developed; based on this model, example AR-RABBIT results are computed for model and real systems, for a range of RABBIT schemes. These results indicate some of the phenomena to be expected in AR-RABBIT measurements, and suggest various applications of the technique in photoionization metrology. Article history• arXiv (this version) The RABBIT methodology -"reconstruction of attosecond harmonic beating by interference of two-photon transitions" [1] -essentially defines a scheme in which XUV pulses are combined with an IR field, and the two fields are applied to a target gas. The gas is ionized, and the photoelectrons detected. In the typical case, the IR field is at the same fundamental frequency ω as the field used to drive harmonic generation, and the XUV field generated is an atto-second pulse train with harmonic components nω, with odd-n only. In this case, if the intensity of the IR field is low to moderate, the resultant photoelectron spectrum will be comprised of discrete bands corresponding to direct 1-photon XUV ionization, * paul.hockett@nrc.ca and sidebands corresponding to 2-photon XUV+IR transitions [1]. (The energetics of this situation are illustrated in fig. 1.) Temporally, if the XUV pulses are short relative to the IR field cycle, the sidebands will also show significant time-dependence, since they will be sensitive to the optical phase difference between the XUV and IR fields, with an oscillatory frequency of 2ω. In this case, a measurement which is angle-integrated, or made at a single detection geometry, can be viewed as a means to characterising the properties of the XUV pulses (spectral content and optical phase), provided that the ionizing system is simple or otherwise well-characterised [1]; RABBIT can therefore be utilised as a pulse metrology technique [1,2], and this is the typical usage.Conversley, RABBIT can also be regarded as a photoelectron metrology technique, since it is sensitive to the magnitudes and phases of the various photoionization pathways accessed. In contrast to most traditional (energy-resolved) photoelectron spectroscopy techniques, RABBIT has the distinction of interfering pathways resulting from different 1-photon transition energies: it is thus sensitive to the energy-dependence of the photoionization dynamics, as well as to the partial-wave components within each pathway. An angle-resolved (AR) RABBIT measurement is particularly powerful in this regard, since the partial-wave phases are encoded in the angular part of the photoelectron interferogram. Although this is a potentially powerful technique, the underlying photoionization dynamics may be extremely complicated, hence quantitati...

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Time delay in molecular photoionization

Cited by 86 publications

References 61 publications

High harmonic generation-2ω attosecond stereo-photoionization interferometry in N₂

High harmonic generation-2ω attosecond stereo-photoionization interferometry in N₂

Attosecond delays in laser-assisted photodetachment from closed-shell negative ions

Angle-resolved RABBITT: theory and numerics

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Time delay in molecular photoionization

Cited by 86 publications

References 61 publications

High harmonic generation-2ω attosecond stereo-photoionization interferometry in N2

High harmonic generation-2ω attosecond stereo-photoionization interferometry in N2

Attosecond delays in laser-assisted photodetachment from closed-shell negative ions

Angle-resolved RABBITT: theory and numerics

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Resources

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High harmonic generation-2ω attosecond stereo-photoionization interferometry in N₂

High harmonic generation-2ω attosecond stereo-photoionization interferometry in N₂