Field-induced diastereomers for chiral separation

A novel approach for the state-specific enantiomeric enrichment and the spatial separation of enantiomers is presented. Our scheme utilizes techniques from strong-field laser physics, specifically an optical centrifuge in conjunction with a static electric field, to create a chiral field with defined handedness. Molecular enantiomers experience unique rotational excitation dynamics and this can be exploited to spatially separate the enantiomers using electrostatic deflection. Notably, the rotational-state-specific enantiomeric enhancement and its handedness is fully controllable. To explain these effects, we introduce the conceptual framework of $field\text{-}induced~diastereomers$ of a chiral molecule and perform robust quantum mechanical simulations on the prototypical chiral molecule propylene oxide (C$_3$H$_6$O), for which ensembles with an enantiomeric excess of up to $30~\%$ were obtained

Ultrafast light-induced dynamics in solvated biomolecules: The indole chromophore with water

Interactions between proteins and their solvent environment can be studied in a bottom-up approach using hydrogen-bonded chromophore-solvent clusters. The ultrafast dynamics following UV-light-induced electronic excitation of the chromophores, potential radiation-damage, and their dependence on solvation are important open questions. The microsolvation effect is challenging to study due to the inherent mix of the produced gas-phase aggregates. We used the deflector to spatially separate different molecular species in combination with pump-probe velocity-map-imaging experiments. We demonstrated that this powerful experimental approach reveals intimate details of the UV-induced dynamics in the near-UV-absorbing prototypical biomolecular indole-water system. We determined the time-dependent appearance of the different reaction products and disentangled the occurring ultrafast processes. This novel approach ensures that the reactants are well-known and that detailed characteristics of the specific reaction products are accessible -- paving the way for the complete chemical-reactivity experiment

Cultuur als antwoord

Indonesi

Knife edge skimming for improved separation of molecular species by the deflector

A knife edge for shaping a molecular beam is described to improve the spatial separation of the species in a molecular beam by the electrostatic deflector. The spatial separation of different molecular species from each other as well as from atomic seed gas is improved. The column density of the selected molecular-beam part in the interaction zone, which corresponds to higher signal rates, was enhanced by a factor of 1.5, limited by the virtual source size of the molecular beam.Comment: 3 pages, 2 figure

Spatial separation of pyrrole and pyrrole-water clusters

We demonstrate the spatial separation of pyrrole and pyrrole(H$_2$O) clusters from the other atomic and molecular species in a supersonically-expanded beam of pyrrole and traces of water seeded in high-pressure helium gas. The experimental results are quantitatively supported by simulations. The obtained pyrrole(H$_2$O) cluster beam has a purity of ~100 %. The extracted rotational temperature of pyrrole and pyrrole(H$_2$O) from the original supersonic expansion is $T_\text{rot}=0.8\pm0.2$ K, whereas the temperature of the deflected, pure-pyrrole(H$_2$O) part of the molecular beam corresponds to $T_\text{rot}\approx0.4$ K

IndustReal: A Dataset for Procedure Step Recognition Handling Execution Errors in Egocentric Videos in an Industrial-Like Setting

Although action recognition for procedural tasks has received notable attention, it has a fundamental flaw in that no measure of success for actions is provided. This limits the applicability of such systems especially within the industrial domain, since the outcome of procedural actions is often significantly more important than the mere execution. To address this limitation, we define the novel task of procedure step recognition (PSR), focusing on recognizing the correct completion and order of procedural steps. Alongside the new task, we also present the multi-modal IndustReal dataset. Unlike currently available datasets, IndustReal contains procedural errors (such as omissions) as well as execution errors. A significant part of these errors are exclusively present in the validation and test sets, making IndustReal suitable to evaluate robustness of algorithms to new, unseen mistakes. Additionally, to encourage reproducibility and allow for scalable approaches trained on synthetic data, the 3D models of all parts are publicly available. Annotations and benchmark performance are provided for action recognition and assembly state detection, as well as the new PSR task. IndustReal, along with the code and model weights, is available at: https://github.com/TimSchoonbeek/IndustReal .Comment: Accepted for WACV 2024. 15 pages, 9 figures, including supplementary material

Strong-field ionization of complex molecules

Strong-field photoelectron momentum imaging of the prototypical biomolecule indole was disentangled in a combined experimental and computational approach. Experimentally, strong control over the molecules enabled the acquisition of photoelectron momentum distributions in the molecular frame for a well-defined, narrow range of incident intensities. A novel, highly efficient semiclassical simulation setup based on the adiabatic tunneling theory quantitatively reproduced these results. Jointly, experiment and computations revealed holographic structures in the asymptotic momentum distributions, which were found to sensitively depend on the alignment of the molecular frame. We identified the essential molecular properties that shape the photoelectron wavepacket in the first step of the ionization process and employ a quantum-chemically exact description of the cation during the subsequent continuum dynamics. The detailed modeling of the molecular ion, which accounts for its polarization by the laser-electric field, enables the simulation of laser-induced electron diffraction off large and complex molecules and provides full insight into the photoelectron's dynamics in terms of semiclassical trajectories. This provides the computational means to unravel strong-field diffractive imaging of biomolecular systems on femtosecond time scales