Velocity map imaging of ions and electrons using electrostatic lenses: Application in photoelectron and photofragment ion imaging of molecular oxygen

Eppink, André T. J. B.; Parker, David H.

doi:10.1063/1.1148310

Cited by 2,626 publications

(2,147 citation statements)

References 33 publications

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“…21 The Integrated photoelectron images are symmetrized to account for detector inhomogeneities and converted into three-dimensional momentum distributions by standard methods. 22 From these, photoelectron kinetic energy (eKE) and angular distributions are readily obtained.…”

Section: Methodsmentioning

confidence: 99%

Dynamics of Electron Solvation in Molecular Clusters

Ehrler

Neumark

2009

Acc. Chem. Res.

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S olvated electrons, and hydrated electrons in particular, are important species in condensed phase chemistry, physics, and biology. Many studies have examined the formation mechanism, reactivity, spectroscopy, and dynamics of electrons in aqueous solution and other solvents, leading to a fundamental understanding of the electron-solvent interaction. However, key aspects of solvated electrons remain controversial, and the interaction between hydrated electrons and water is of central interest. For example, although researchers generally accept that hydrated electrons, e aq -, occupy solvent cavities, another picture suggests that the electron resides in a diffuse orbital localized on a H 3 O radical. In addition, researchers have proposed two physically distinct models for the relaxation mechanism when the electron is excited. These models, formulated to interpret condensed phase experiments, have markedly different time scales for the internal conversion from the excited p state to the ground s state.Studies of negatively charged clusters, such as (H 2 O) n -and I -(H 2 O) n , offer a complementary perspective for studying aqueous electron solvation. In this Account, we use time-resolved photoelectron spectroscopy (TRPES), a femtosecond pump-probe technique in which mass-selected anions are electronically excited and then photodetached at a series of delay times, to focus on time-resolved dynamics in these and similar species. In (H 2 O) n -, TRPES gives evidence for ultrafast internal conversion in clusters up to n ) 100. Extrapolation of these results yields a p-state lifetime of 50 fs in the bulk limit. This is in good agreement with the nonadiabatic solvation model, one of the models proposed for relaxation of e aq -. Similarly, experiments on (MeOH) n -up to n ) 450 give an extrapolated p-state lifetime of 150 fs.TRPES investigations of I -(H 2 O) n and I -(CH 3 CN) n probe a different aspect of electron solvation dynamics. In these experiments, an ultraviolet pump pulse excites the cluster analog of the charge-transfer-to-solvent (CTTS) band, ejecting an electron from the iodide into the solvent network. The probe pulse then monitors the solvent response to this excess electron, specifically its stabilization via solvent rearrangement. In I -(H 2 O) n , the iodide sits outside the solvent network, as does the excess electron initially formed by CTTS excitation. However, the iodide in I -(CH 3 CN) n is internally solvated, and both experimental and theoretical evidence indicate that electrons in (CH 3 CN) n -are internally solvated. Hence, these experiments reflect the complex dynamics that ensue when the electron is photodetached within a highly confined solvent cavity.

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Section: Methodsmentioning

confidence: 99%

Dynamics of Electron Solvation in Molecular Clusters

Ehrler

Neumark

2009

Acc. Chem. Res.

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“…R6 houses the photoelectron velocity map imaging (VMI) detection arrangement, which is shown in greater detail in Figure 2b. A typical VMI arrangement oriented perpendicular to the ion beam axis with a design similar to that used by Eppink and Parker 24 would generate a potential difference of ~250 V. This is sufficient to deflect the ion beam into the VMI electrodes before it reaches the laser interaction volume. In order to avoid this, the VMI electrodes may be rapidly pulsed.…”

Section: Laser System and Detection Regionmentioning

confidence: 99%

Ultrafast Relaxation Dynamics Observed Through Time-Resolved Photoelectron Angular Distributions

et al. 2010

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The 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.

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“…2 In simple systems the PE angular distribution (PAD) can be well described by the Cooper-Zare formalism 3 in which the partial waves and their interference determine the observed 25 PE anisotropy. This works particularly well for atomic photodetachment.…”

Section: Introductionmentioning

confidence: 99%

Effects of resonant excitation, pulse duration and intensity on photoelectron imaging of a dianion

Chatterley

Horke

Verlet

2014

Phys. Chem. Chem. Phys.

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. (2014) 'E ects of resonant excitation, pulse duration and intensity on photoelectron imaging of a dianion.', Physical chemistry chemical physics., 16 (2). pp. 489-496. Further information on publisher's website:http://dx.doi.org/10.1039/c3cp53235fPublisher's copyright statement:Additional information: 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. The photoelectron imaging of the indigo carmine dianion is used to demonstrate the effects of resonance excitation, pulse duration and pulse intensity on the photoelectron spectra and angular distributions of a dianion. Excitation of the S 1 state leads to an aligned distribution of excited state dianions. The photoelectron angular distribution following subsequent photodetachment within a femtosecond laser pulse is primarily determined by the repulsive Coulomb barrier. Extending the timescale for 10 photodetachment to nanoseconds leads to dramatic changes in both the spectra and angular distributions. These observations are explained in terms of statistical detachment of electrons, either from the monoanion, or from the ground state of the dianion following a number of photon cycles trough the S 1 ← S 0 transition. At high intensity, new electron emission channels open up, leading to emission below the repulsive Coulomb barrier. This has been assigned to strong-field induced detachment and the effect of an 15 electric field on the Coulomb barrier is discussed in terms of the photoelectron spectra and angular distributions.

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Velocity map imaging of ions and electrons using electrostatic lenses: Application in photoelectron and photofragment ion imaging of molecular oxygen

Cited by 2,626 publications

References 33 publications

Dynamics of Electron Solvation in Molecular Clusters

Dynamics of Electron Solvation in Molecular Clusters

Ultrafast Relaxation Dynamics Observed Through Time-Resolved Photoelectron Angular Distributions

Effects of resonant excitation, pulse duration and intensity on photoelectron imaging of a dianion

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