Gregor Kastirke

Tracking the Complex Dynamics of Electron-Transfer-Mediated Decay in Real Space and Time

Florian Trinter, Jaroslav Hofierka, J. Rist, M. Kircher et autres

decay channels, nuclear dynamics play a crucial role as they have a direct impact on the decay efficiency itself. Here, we present a detailed study of the electron-transfer-mediated decay in a loosely bound triatomic prototype system, combining experimental results from a 5-fold …

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Tracking the Complex Dynamics of Electron-Transfer-Mediated Decay in Real Space and Time

Florian Trinter, Jaroslav Hofierka, J. Rist, M. Kircher et autres

When an electronically excited atom or molecule is embedded in a chemical environment as, e.g., in a liquid or a loosely bound cluster, it can de-excite through mechanisms where neighboring atoms or molecules are actively participating in the decay: either by donating …

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Imaging collective quantum fluctuations of the structure of a complex molecule

Benoît Richard, Rebecca Boll, Sourav Banerjee, Julia M. Schäfer et autres

Because of the Heisenberg uncertainty principle, the structure of a molecule fluctuates about its mean geometry, even in the ground state. Observing this fundamental quantum effect experimentally-particularly, revealing the collective nature of the structural quantum fluctuations-remains an unmet challenge for complex molecules. …

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State selectivity in core ionization of methane

Jyoti Rajput, Jonathan Stindl, A. Cassimi, B. Gervais et autres

A clear experimental signature of the population of the lowest triplet state T 1 3 of the methane dication is identified in a photoionization experiment. This state is populated only in valence ionization and is absent when the dication is formed by …

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Direct observation of ultrafast symmetry reduction during internal conversion of 2-thiouracil using Coulomb explosion imaging

T. Jahnke, Sebastian Mai, Surjendu Bhattacharyya, Keyu Chen et autres

The photochemistry of heterocyclic molecules plays a decisive role for processes and applications like DNA photo-protection from UV damage and organic photocatalysis. The photochemical reactivity of heterocycles is determined by the redistribution of photoenergy into electronic and nuclear degrees of freedom, initially …

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X-ray-Induced Molecular Catapult: Ultrafast Dynamics Driven by Lightweight Linkages

Oksana Travnikova, Victor Kimberg, Barbara Cunha de Miranda, Florian Trinter et autres

In our work, we demonstrate that X-ray photons can initiate a “molecular catapult” effect, leading to the dissociation of chemical bonds and the formation of heavy fragments within just a few femtoseconds. We reconstruct the momenta of fragments from a three-body dissociation …

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Experimental Observation of Non-Exponential Auger-Meitner Decay of Inner-Shell-Excited CO

Miriam Weller, Gregor Kastirke, J. Rist, Claudia Goy et autres

Electronically excited atoms or molecules may deexcite by emission of a secondary electron through an Auger-Meitner decay. This deexcitation process is typically considered to be exponential in time. This is strictly speaking, however, only true for the case of an atom. Here, …

Role of the Binding Energy on Nondipole Effects in Single-Photon Ionization

Marius A. Schmidt, N. Melzer, M. Kircher, Gregor Kastirke et autres

We experimentally study the influence of the binding energy on nondipole effects in K-shell single-photon ionization of atoms at high photon energies. We find that for each ionization event, as expected by momentum conservation, the photon momentum is transferred almost fully to …

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Direct observation of ultrafast symmetry reduction during internal conversion of 2-thiouracil using Coulomb explosion imaging

T. Jahnke, Sebastian Mai, Surjendu Bhattacharyya, Keyu Chen et autres

Molecular photoabsorption results in an electronic excitation/ionization which couples to the rearrangement of the nuclei. The resulting intertwined change of nuclear and electronic degrees of freedom determines the conversion of photoenergy into other molecular energy forms. Nucleobases are excellent candidates for studying …

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Observation of a collective two-electron molecular resonance

J. Rist, Miriam Weller, M. Kircher, D. Trabert et autres

Unbound electrons can experience resonant scattering and transient trapping in a molecular potential. In molecular photoemission, these shape resonances manifest as peaks in the cross section with a width of several electron volts. They depend on the details of the molecular potential …

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Mechanisms of one-photon two-site double ionization after resonant inner-valence excitation in Ne clusters

Andreas Hans, Florian Trinter, Philipp Schmidt, S. Eckart et autres

The role of interatomic and intermolecular energy and charge-transfer processes in weakly bound matter is currently lively debated due to emerging destructive low-energy electrons and radicals. Here, we discuss two mechanisms of single-photon two-site double ionization occurring competitively or subsequently to resonant …

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Molecular-frame differential photoelectron circular dichroism of O 1s-photoelectrons of trifluoromethyloxirane

G. Nalin, Nikolay M. Novikovskiy, K. Fehre, N. Anders et autres

The differential photoelectron circular dichroism (PECD) of O $1s$ photoelectrons of $R$-trifluoromethyloxirane enantiomers as a function of the photoelectron emission direction in the molecular frame of reference and the direction from which circularly polarized light hits the molecule, is studied experimentally and …

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