Subfemtosecond steering of hydrocarbon deprotonation through superposition of vibrational modes

Alnaser, A. S.; Kübel, Matthias; Siemering, R.; Bergues, Boris; Kling, Nora G.; Betsch, K. J.; Deng, Yunpei; Schmidt, Jürgen; Alahmed, Z. A.; Azzeer, Abdallah M.; Ullrich, J.; Ben‐Itzhak, I.; Moshammer, R.; Kleineberg, Ulf; Krausz, Ferenc; Vivie‐Riedle, Regina de; Kling, Matthias F.

doi:10.1038/ncomms4800

Cited by 85 publications

(96 citation statements)

References 34 publications

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“…The 3100 nm pulse triggers molecular dissociation and, at the same time, collects structural snapshots of the entire acetylene molecule. The alignment dependent dynamics (23) are structurally imaged for both orientations We chose acetylene because it is one of the best studied hydrocarbons (24)(25)(26)(27) and offers the numerous degrees of freedom and multitude of structural dynamics found also in larger and more complex molecules (1,28,29). Note that due to the strong field nature of LIED, many different fragmentation channels and ionization states occur simultaneously.…”

Section: One Sentence Summarymentioning

confidence: 99%

Ultrafast electron diffraction imaging of bond breaking in di-ionized acetylene

Wolter

Pullen

et al. 2016

Science

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Visualizing chemical reactions as they occur requires atomic spatial and femtosecond temporal resolution. Here, we report imaging of the molecular structure of acetylene 9 fs after ionization. Using mid-infrared laser induced electron diffraction (LIED) we obtain snapshots as a proton departs the [C 2 H 2 ] 2+ ion. By introducing an additional laser field, we also demonstrate control over the ultrafast dissociation process and resolve different bond dynamics for molecules oriented parallel vs. perpendicular to the LIED field. These measurements are in excellent agreement with a quantum chemical description of fielddressed molecular dynamics. One Sentence Summary:We demonstrate space and time imaging of a single acetylene molecule after 9 fs while one of its bonds is broken and a proton departs the molecule.Ultrafast imaging of atomic motion in real time during transitions in molecular structure is prerequisite to disentangling the complex interplay between reactants and products (1, 2) since the motion of all atoms are coupled. Ultrafast absorption and emission spectroscopic techniques have uncovered numerous insights in chemical reaction dynamics (3,4), but are limited by their reliance on local chromophores and their associated ladders of quantum states rather than global structural characterization. Reaction imaging at the molecular level requires a combination of few-femtosecond temporal and picometer spatial measurement resolution (5). Amongst the many techniques that are currently under intense development, x-ray scattering can reach few-femtosecond pulse durations at photon energies of 8.3 keV (1.5 Å) (6) with a demonstrated measurement resolution of 3.5 Å (7). Challenges for such photonbased approaches are the coarse spatial resolution and the low scattering cross-sections, especially for gas phase investigations. Electron scattering (8) provides much larger interaction cross-sections and smaller de Broglie wavelengths, but suffers from space charge broadening which decreases the temporal resolution.Consequently, measurements have demonstrated 7 pm spatial and 100 fs temporal resolution (9, 10) in gas phase experiments. Remedies to improve temporal resolution include relativistic electron acceleration (11) or electron bunch compression (12) with 100 fs and 28 fs limits, respectively. Compared to such incoherent scattering of electrons from an electron source off a molecular target, laser induced electron diffraction (LIED) is a self-imaging method based on coherent electron scattering (13)(14)(15)(16)(17). In LIED, one electron which is liberated from the target molecule through tunnel ionization, it is then accelerated in the field and rescattered of its molecular ion thereby acquiring structural information. The electron recollision process occurs within one optical cycle of the laser field and permits mapping electron momenta to recollision time (18,19).Here, we used LIED to image an entire hydrocarbon molecule (acetylene -C 2 H 2 ) at 9 fs after ionizationtriggered dissociation and visualiz...

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Section: One Sentence Summarymentioning

confidence: 99%

Ultrafast electron diffraction imaging of bond breaking in di-ionized acetylene

Wolter

Pullen

et al. 2016

Science

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268

236

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“…Traditionally, femtochemistry employs temporally shaped femtosecond laser pulses to steer the nuclear vibrational dynamics to control the formation or breakage of molecular bonds [3]. In recent years, laser pulses with high intensity and ultrashort pulse duration were successfully applied to the control of molecular fragmentation and isomerization reactions through strong field ionization or excitation [4][5][6][7][8][9][10]. Such molecular fragmentation is a process involving one or more bond breakages during or after the interaction of a molecule with a strong laser field [11].…”

Section: Introductionmentioning

confidence: 99%

Fragmentation of long-lived hydrocarbons after strong field ionization

et al. 2016

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We experimentally and theoretically investigated the deprotonation process on nanosecond to microsecond timescale in ethylene and acetylene molecules, following their double ionization by a strong femtosecond laser field. In our experiments we utilized coincidence detection with the reaction microscope technique, and found that both the lifetime of the long-lived ethylene dication leading to the delayed deprotonation and the relative channel strength of the delayed deprotonation compared to the prompt one have no evident dependence on the laser pulse duration and the laser peak intensity. Quantum chemical simulations suggest that such delayed fragmentation originates from the tunneling of near-dissociation-threshold vibrational states through a dissociation barrier on a dication electronic state along C-H stretching. Such vibrational states can be populated through strong field double ionization induced vibrational excitation on an electronically excited state in the case of ethylene, and through intersystem crossing from electronically excited states to the electronic ground state in the case of acetylene.

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“…The cosine wave gives rise to a smooth spectrum in the cutoff range, suggesting emission in a single burst of potentially sub-fs duration, whereas the appearance of modulation for the sine wave suggests that that the emission is distributed in two bursts half a cycle apart. complex molecules [33,34] or towards the sub-cycle manipulation of EUV generation in strongly driven surface plasmas [35] and the photoemission from metal nanotips [36].…”

Section: Attosecond Strong-field Physics In the Few-cycle Regimementioning

confidence: 99%

MAKING OPTICAL WAVES, TRACING ELECTRONS IN REAL-TIME: THE ONSET OF THE ATTOSECOND REALM (Invited Review)

Goulielmakis¹,

Krausz²

2014

PIER

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Abstract-Tracing the dynamics of electrons inside atoms molecules or solids as they occur in real time resides at the forefront of modern science and technology. Advances in attosecond physics over the last decade and beyond are now enabling this essential experimental capability. Here we discuss some of the key developments in light sciences that made possible attosecond metrology and control of electronic processes inside matter on native time scales. These developments hold the promise for new, fundamental insights into the innerworkings of the microcosm as well as the identification of innovative routes for light-based electronic and photonic devices operating at PHz rates.

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Subfemtosecond steering of hydrocarbon deprotonation through superposition of vibrational modes

Cited by 85 publications

References 34 publications

Ultrafast electron diffraction imaging of bond breaking in di-ionized acetylene

Ultrafast electron diffraction imaging of bond breaking in di-ionized acetylene

Fragmentation of long-lived hydrocarbons after strong field ionization

MAKING OPTICAL WAVES, TRACING ELECTRONS IN REAL-TIME: THE ONSET OF THE ATTOSECOND REALM (Invited Review)

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