Photoelectron-Photoion Momentum Spectroscopy as a Clock for Chemical Rearrangements: Isomerization of the Di-Cation of Acetylene to the Vinylidene Configuration

Osipov, T.; Cocke, C. L.; Prior, M. H.; Landers, A. L.; Weber, Thorsten; Jagutzki, O.; Schmidt, L. Ph. H.; Schmidt‐Böcking, H.; Dörner, R.

doi:10.1103/physrevlett.90.233002

Cited by 120 publications

(96 citation statements)

References 21 publications

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“…This is consistent with the upper limit for the isomerization time reported in ref. 1. The increase in the bending angle at 12 fs, compared with 0 fs, is followed by a discernible decrease at 25 fs.…”

Section: Resultsmentioning

confidence: 89%

“…3h, we plot the time dependence of the ratio of the signal in the region (1) to that in the area in the vicinity of the left carbon (region (2), as illustrated in Fig. 3a).…”

Section: Resultsmentioning

confidence: 99%

“…Measurements reported by Osipov et al 1,2 indicate that, when initiated by X-ray core ionization, this isomerization can occur on a timescale shorter than 60 fs. This ultrafast rate was unexpected based on the predicted barrier heights in the electronic states populated in relaxation on core ionization 3,4 .…”

mentioning

confidence: 95%

“…Isomerization of acetylene (HCCH) to form vinylidene (H 2 CC) has been studied in the neutral molecule, as well as singly and doubly charged acetylene ions 1,2,[24][25][26][27][28][29][30][31][32][33][34][35][36] . Acetylene cations are important not only as a model for molecular dynamics and radiation damage investigations, but also in a range of applications, from plasma devices 37 , combustion 38 , semiconductor manufacturing 39 and to understanding planetary atmospheres 40 .…”

mentioning

confidence: 99%

“…Acetylene cations are important not only as a model for molecular dynamics and radiation damage investigations, but also in a range of applications, from plasma devices 37 , combustion 38 , semiconductor manufacturing 39 and to understanding planetary atmospheres 40 . Isomerization of the dication has been investigated in synchrotron experiments 1,2,27,28,34 . Osipov et al 1,2 performed ion-ionphotoelectron and ion-ion-Auger electron coincidence measurements to study the fragmentation of the dication formed on core ionization of acetylene.…”

mentioning

confidence: 99%

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Ultrafast isomerization initiated by X-ray core ionization

et al. 2015

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Rapid proton migration is a key process in hydrocarbon photochemistry. Charge migration and subsequent proton motion can mitigate radiation damage when heavier atoms absorb X-rays. If rapid enough, this can improve the fidelity of diffract-before-destroy measurements of biomolecular structure at X-ray-free electron lasers. Here we study X-ray-initiated isomerization of acetylene, a model for proton dynamics in hydrocarbons. Our time-resolved measurements capture the transient motion of protons following X-ray ionization of carbon K-shell electrons. We Coulomb-explode the molecule with a second precisely delayed X-ray pulse and then record all the fragment momenta. These snapshots at different delays are combined into a 'molecular movie' of the evolving molecule, which shows substantial proton redistribution within the first 12 fs. We conclude that significant proton motion occurs on a timescale comparable to the Auger relaxation that refills the K-shell vacancy.

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Section: Resultsmentioning

confidence: 89%

“…3h, we plot the time dependence of the ratio of the signal in the region (1) to that in the area in the vicinity of the left carbon (region (2), as illustrated in Fig. 3a).…”

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 95%

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confidence: 99%

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confidence: 99%

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Ultrafast isomerization initiated by X-ray core ionization

et al. 2015

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Accurate Quantum Dynamics Study on the Resonance Decay of Vinylidene

Ren

Bian

2011

ChemPhysChem

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Hydrogen (H) migration/proton transfer is widely regarded as being of paramount importance in different fields. [1,2] As H migration processes involve hydrogen, the most "quantum" of atoms, quantum dynamical (QD) effects such as tunneling often play a significant role, and the understanding of the nature of these processes thus requires that accurate full-dimensional QD calculations be performed. However, such calculations are very challenging, even for the benchmark vinylidene-acetylene system. Herein, we propose a simple functional form for the isomerization coordinate of 1,2-H migration, and by combining this with a complex absorbing potential and Hamiltonian in Jacobi coordinates, we achieve the first accurate QD calculations of resonance decay (RD) lifetimes of vinylidene, providing a probe to the vibrationally resolved rate of H migration. Our calculational results provide new insights at the quantum-state level, and the findings are important for acquiring a deeper understanding of H migration processes.Vinylidene (H 2 C=C:) is a vital reactive intermediate in the combustion of hydrocarbon. The isomerization between vinylidene and acetylene is an important prototype of intramolecular H migration, and has attracted much attention; [3][4][5][6][7][8][9][10][11][12][13][14][15] however, the key issue related to the lifetime of vinylidene has not been resolved so far. For example, the lifetime of vinylidene was estimated to be 0.04-0.2 ps based on a simulation of line shapes by the Lineberger group using photoelectron spectroscopy of vinylidene anion;[4] while a very long lifetime of at least 3.5 ms was claimed by Vager et al. in their coulomb explosion imaging (CEI) experiments.[5] Approximate QD calculations [7,8,10,15] also yielded lifetimes with large discrepancies. The present QD calculations also make it possible to clarify the inconsistency among previous studies on the lifetime of vinylidene. We use CC-HH Jacobi coordinates (see Figure 1 a) to represent the nuclear motion, and the Hamiltonian with a complex absorbing potential (CAP) can be written as [Eq. (1) In Equation (1),ĵ i (i = 1,2) is the angular momentum operator associated with r i ;ĵ 12 is the vector addition ofĵ 1 andĵ 2 ; and s is the isomerization coordinate. To compute the RD lifetime of vinylidene, the introduction of V CAP is essential. The CAP is a kind of useful theoretical tool, with which the resonance states could be directly computed using methods similar to those for bound-state problems; [16,17] the eigenvalue of a CAP-modified Hamiltonian takes a complex form [Eq. (2)]:

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Chemische Reaktionen in Superzeitlupe

Moshammer

Rudenko

Ullrich

2013

Physik in unserer Zeit

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Einen neuen Weg in die Femtochemie eröffnen die intensiven Femtosekunden-Lichtpulse im extremen Ultraviolett (EUV) aus dem Freie-Elektronen-Laser in Hamburg (FLASH) zusammen mit einer ausgefeilten Pump-Probe-Apparatur. Damit konnte erstmals die lichtinduzierte Umwandlung eines Acetylenmoleküls in sein Isomer Vinyliden in drei Dimensionen als “Zeitlupenfilm” visualisiert werden. Ein EUV-Puls ionisiert zunächst das Acetylen, das seine Kernbausteine umordnet und allmählich die Form von Vinyliden annimmt. Ein zweiter, sehr intensiver Lichtpuls ionisiert es währenddessen weiter, so dass es explodiert. Aus der präzisen Erfassung der Fragmente gelingt eine genaue Rekonstruktion der geometrischen Struktur des Moleküls zum Explosionszeitpunkt. Der Ablauf dieser Isomerisierungsreaktion lässt sich durch Variation des Zeitabstands zwischen Pump- und Probepuls in Raum und Zeit präzise verfolgen. In Zukunft sollen damit chemische Reaktionen mit Femtosekunden-Auflösung “gefilmt” werden, die für Biologie und Anwendungen wichtig sind

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Photoelectron-Photoion Momentum Spectroscopy as a Clock for Chemical Rearrangements: Isomerization of the Di-Cation of Acetylene to the Vinylidene Configuration

Cited by 120 publications

References 21 publications

Ultrafast isomerization initiated by X-ray core ionization

Ultrafast isomerization initiated by X-ray core ionization

Accurate Quantum Dynamics Study on the Resonance Decay of Vinylidene

Chemische Reaktionen in Superzeitlupe

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