Momentum-map-imaging photoelectron spectroscopy of fullerenes with femtosecond laser pulses

Kjellberg, Mikael; Johansson, J. Olof; Jonsson, Fabian; Bulgakov, Alexander V.; Bordas, C.; Campbell, Eleanor E. B.; Hansen, Klavs

doi:10.1103/physreva.81.023202

Cited by 52 publications

(70 citation statements)

References 24 publications

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“…A further limitation of the BUU/VUU approach appears in the case of clusters: it is not clear that it could be used in systems others than simple alkalines, where electron wave functions are sufficiently delocalised and smooth to allow a semi-classical treatment [22]. This hinders, e.g., an application to C 60 which is one of the systems attracting the most elaborate analysis of dissipative dynamics so far [7,23]. It should finally be noted that even in the high-excitation domain a major de-excitation channel is ionization which may quickly take away large amounts of excitation energy cooling the system down into a regime where quantum effects cannot be neglected any more.…”

Section: Introductionmentioning

confidence: 99%

A quantum relaxation-time approximation for finite fermion systems

Reinhard

Suraud

2015

Annals of Physics

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We propose a relaxation time approximation for the description of the dynamics of strongly excited fermion systems. Our approach is based on time-dependent density functional theory at the level of the local density approximation. This mean-field picture is augmented by collisional correlations handled in relaxation time approximation which is inspired from the corresponding semi-classical picture. The method involves the estimate of microscopic relaxation rates/times which is presently taken from the well established semi-classical experience. The relaxation time approximation implies evaluation of the instantaneous equilibrium state towards which the dynamical state is progressively driven at the pace of the microscopic relaxation time. As test case, we consider Na clusters of various sizes excited either by a swift ion projectile or by a short and intense laser pulse, driven in various dynamical regimes ranging from linear to strongly non-linear reactions. We observe a strong effect of dissipation on sensitive observables such as net ionization and angular distributions of emitted electrons. The effect is especially large for moderate excitations where typical relaxation/dissipation time scales efficiently compete with ionization for dissipating the available excitation energy. Technical details on the actual procedure to implement a working recipe of such a quantum relaxation approximation are given in appendices for completeness.

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Section: Introductionmentioning

confidence: 99%

A quantum relaxation-time approximation for finite fermion systems

Reinhard

Suraud

2015

Annals of Physics

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“…Exponentially decaying PE spectra peaking at threshold are often indicators for statistical autodetachment or thermionic emission. [47][48][49][50] Taking the above observations into account, and the fact that no fragmentation is expected following a single excitation to the S 1 state, we recognize that the system must be acquiring excessive amounts of internal energy, which can then lead to dissociation and electron loss.…”

mentioning

confidence: 99%

Influence of the repulsive Coulomb barrier on photoelectron spectra and angular distributions in a resonantly excited dianion

Horke

Chatterley

Verlet

2013

The Journal of Chemical Physics

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTA photoelectron imaging study of the gas-phase dianion of pyrromethene-556 is presented. The photoelectron spectra and angular distributions following resonant excitation of the S 1 excited state with nanosecond and femtosecond laser pulses are compared, and the influence of the repulsive Coulomb barrier (RCB) in both cases evaluated. Photoelectron angular distributions show the effect of molecular alignment due to an allowed electronic excitation and can be understood qualitatively based on the calculated RCB surface using the Local Static Approximation. Comparison between femtosecond and nanosecond excitation reveals marked differences in the photoelectron spectra. While femtosecond experiments confirm that tunneling through the RCB is adiabatic, nanosecond experiments show a broad photoelectron feature peaking near the RCB maximum. This is explained in terms of the lifetime of internal conversion, which has been determined by time-resolved photoelectron spectroscopy to be ~120 ps: as this is faster than the nanosecond laser pulses, multiple photons can be absorbed through the S 1 ← S 0 transition which leads to large amounts of internal energy and enables electron detachment directly above the RCB. Fragmentation and detachment from the monoanion is also inferred by the presence of photoelectrons emitted at very low kinetic energy. Our results highlight the difficulty in interpreting photoelectron spectra of polyanions in which a resonant state is excited.3

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“…For the two lowest intensities (I 0 and 2I 0 ), they show a dense sequence of peaks which are separated by the photon energy ω las = 1.36 eV. This is the typical pattern for Above-Threshold Ionization (ATI), which has been well studied for C 60 experimentally [60,61] and theoretically [32,33,62]. These equi-spaced patterns are washed out when the laser in-tensity increases to the two highest values (4.6 I 0 , 8 I 0 ).…”

Section: Resultsmentioning

confidence: 79%

Strong-field effects in the photoemission spectrum of theC60fullerene

et al. 2016

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Considering C60 as a model system for describing field emission from the extremity of a carbon nanotip, we explore electron emission from this fullerene excited by an intense, near-infrared, fewcycle laser pulse (10 13 -10 14 W/cm 2 , 912 nm, 8-cycle). To this end, we use time-dependent density functional theory augmented by a self-interaction correction. The ionic background of C60 is described by a soft jellium model. Particular attention is paid to the high energy electrons. Comparing the spectra at different emission angles, we find that, as a major result of this study, the photoelectrons are strongly peaked along the laser polarization axis forming a highly collimated electron beam in the forward direction, especially for the high energy electrons. Moreover, the high-energy plateau cut-off found in the simulations agrees well with estimates from the classical three-step model. We also investigate the build-up of the high-energy part of a photoelectron spectrum by a time-resolved analysis. In particular, the modulation on the plateau can be interpreted as contributions from intracycle and intercycle interferences.

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Momentum-map-imaging photoelectron spectroscopy of fullerenes with femtosecond laser pulses

Cited by 52 publications

References 24 publications

A quantum relaxation-time approximation for finite fermion systems

A quantum relaxation-time approximation for finite fermion systems

Influence of the repulsive Coulomb barrier on photoelectron spectra and angular distributions in a resonantly excited dianion

Strong-field effects in the photoemission spectrum of theC60fullerene

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