10 research outputs found
Photoelectron spectroscopy on magnesium ensembles in helium nanodroplets
The special conditions provided by the ultracold and liquid environment of helium nanodroplets allow the formation of unusual and unique structures from embedded complexes. A recent example is magnesium atoms, which show evidence for the formation of a metastable structure called foam, in which single atoms are separated by a layer of helium. The present work focuses on the electronic properties of the foam, which were studied by photoelectron spectroscopy.Die besonderen Bedingungen der Helium Nanotropfen, die in der ultrakalten und flĂŒssigen Umgebung herrschen, können zu auĂergewöhnlichen und einzigartigen Strukturen eingebetteter Komplexe fĂŒhren. Ein aktuelles Beispiel sind die Magnesiumatome, die Hinweise zeigen auf die Bildung einer metastabilen âSchaumâ-Struktur, bei der einzelne Mg-Atome durch eine Heliumschicht getrennt sind. Der Fokus dieser Arbeit liegt auf den elektronischen Eigenschaften dieses Schaums, die mit Photoelektronenspektroskopie untersucht wurden
Transform-Limited Photon Emission From a Lead-Vacancy Center in Diamond Above 10 K
Transform-limited photon emission from quantum emitters is essential for
high-fidelity entanglement generation. In this study, we report the coherent
optical property of a single negatively-charged lead-vacancy (PbV) center in
diamond. Photoluminescence excitation measurements reveal stable fluorescence
with a linewidth of 39 MHz at 6 K, close to the transform-limit estimated from
the lifetime measurement. We observe four orders of magnitude different
linewidths of the two zero-phonon-lines, and find that that the phonon-induced
relaxation in the ground state contributes to this huge difference in the
linewidth. Due to the suppressed phonon absorption in the PbV center, we
observe nearly transform-limited photon emission up to 16 K, demonstrating its
high temperature robustness compared to other color centers in diamond.Comment: 13 pages,4 figure
Efficient laser-driven proton acceleration from cylindrical and planar cryogenic hydrogen jets.
We report on recent experimental results deploying a continuous cryogenic hydrogen jet as a debris-free, renewable laser-driven source of pure proton beams generated at the 150âTW ultrashort pulse laser Draco. Efficient proton acceleration reaching cut-off energies of up to 20âMeV with particle numbers exceeding 109 particles per MeV per steradian is demonstrated, showing for the first time that the acceleration performance is comparable to solid foil targets with thicknesses in the micrometer range. Two different target geometries are presented and their proton beam deliverance characterized: cylindrical (â
5âÎŒm) and planar (20âÎŒmâĂâ2âÎŒm). In both cases typical Target Normal Sheath Acceleration emission patterns with exponential proton energy spectra are detected. Significantly higher proton numbers in laser-forward direction are observed when deploying the planar jet as compared to the cylindrical jet case. This is confirmed by two-dimensional Particle-in-Cell (2D3V PIC) simulations, which demonstrate that the planar jet proves favorable as its geometry leads to more optimized acceleration conditions
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Efficient laser-driven proton acceleration from cylindrical and planar cryogenic hydrogen jets
We report on recent experimental results deploying a continuous cryogenic hydrogen jet as a debris-free, renewable laser-driven source of pure proton beams generated at the 150âTW ultrashort pulse laser Draco. Efficient proton acceleration reaching cut-off energies of up to 20âMeV with particle numbers exceeding 109 particles per MeV per steradian is demonstrated, showing for the first time that the acceleration performance is comparable to solid foil targets with thicknesses in the micrometer range. Two different target geometries are presented and their proton beam deliverance characterized: cylindrical (â
5âÎŒm) and planar (20âÎŒmâĂâ2âÎŒm). In both cases typical Target Normal Sheath Acceleration emission patterns with exponential proton energy spectra are detected. Significantly higher proton numbers in laser-forward direction are observed when deploying the planar jet as compared to the cylindrical jet case. This is confirmed by two-dimensional Particle-in-Cell (2D3V PIC) simulations, which demonstrate that the planar jet proves favorable as its geometry leads to more optimized acceleration conditions
Formation of coherent rotational wavepackets in small molecule-helium clusters using impulsive alignment
Revealing the origin of fast delayed fluorescence in a donor functionalized bisterpyridine
This project has been partly funded by the European Union Horizon 2021 research and innovation programme under grant agreement No.â
101073045 (TADFsolutions). M.â
C.â
G. acknowledges financial support by the Alexander von Humboldt Stiftung (Humboldt professorship). F.â
J. acknowledges support by BMBF and EU via QSens, H2020 ERC HyperQ project (856432), QCIRCLE (101059999, HORIZON), QuMicro (101046911, HORIZON), and FLORIN (101086142, HORIZON). Open Access funding enabled and organized by Projekt DEAL.A new carbazole-substituted bisterpyridine with pronounced delayed fluorescence is presented. While the molecular donor-acceptor-donor design suggests the origin of this to be thermally activated delayed fluorescence (TADF), results from various photophysical characterizations, OLED characteristics, temperature-dependent NMR spectroscopy, and DFT calculations all point against the involvement of triplet states. The molecule exhibits blue emission at about 440â
nm with two or more fast decay channels in the lower nanosecond range in both solution and thin films. The delayed emission is proposed to be caused by rotational vibrational modes. We suggest that these results are generally applicable, especially for more complex molecules, and should be considered as alternative or competitive emissive relaxation pathways in the field of organic light emitting materials.Publisher PDFPeer reviewe
Revealing the origin of fast delayed fluorescence in a donor functionalized bisterpyridine
A new carbazole-substituted bisterpyridine with pronounced delayed fluorescence is presented. While the molecular donor-acceptor-donor design suggests the origin of this to be thermally activated delayed fluorescence (TADF), results from various photophysical characterizations, OLED characteristics, temperature-dependent NMR spectroscopy, and DFT calculations all point against the involvement of triplet states. The molecule exhibits blue emission at about 440â
nm with two or more fast decay channels in the lower nanosecond range in both solution and thin films. The delayed emission is proposed to be caused by rotational vibrational modes. We suggest that these results are generally applicable, especially for more complex molecules, and should be considered as alternative or competitive emissive relaxation pathways in the field of organic light emitting materials
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Efficient laser-driven proton acceleration from cylindrical and planar cryogenic hydrogen jets.
We report on recent experimental results deploying a continuous cryogenic hydrogen jet as a debris-free, renewable laser-driven source of pure proton beams generated at the 150âTW ultrashort pulse laser Draco. Efficient proton acceleration reaching cut-off energies of up to 20âMeV with particle numbers exceeding 109 particles per MeV per steradian is demonstrated, showing for the first time that the acceleration performance is comparable to solid foil targets with thicknesses in the micrometer range. Two different target geometries are presented and their proton beam deliverance characterized: cylindrical (â
5âÎŒm) and planar (20âÎŒmâĂâ2âÎŒm). In both cases typical Target Normal Sheath Acceleration emission patterns with exponential proton energy spectra are detected. Significantly higher proton numbers in laser-forward direction are observed when deploying the planar jet as compared to the cylindrical jet case. This is confirmed by two-dimensional Particle-in-Cell (2D3V PIC) simulations, which demonstrate that the planar jet proves favorable as its geometry leads to more optimized acceleration conditions
Efficient laser-driven proton acceleration from cylindrical and planar cryogenic hydrogen jets
Abstract We report on recent experimental results deploying a continuous cryogenic hydrogen jet as a debris-free, renewable laser-driven source of pure proton beams generated at the 150âTW ultrashort pulse laser Draco. Efficient proton acceleration reaching cut-off energies of up to 20âMeV with particle numbers exceeding 109 particles per MeV per steradian is demonstrated, showing for the first time that the acceleration performance is comparable to solid foil targets with thicknesses in the micrometer range. Two different target geometries are presented and their proton beam deliverance characterized: cylindrical (â
5âÎŒm) and planar (20âÎŒmâĂâ2âÎŒm). In both cases typical Target Normal Sheath Acceleration emission patterns with exponential proton energy spectra are detected. Significantly higher proton numbers in laser-forward direction are observed when deploying the planar jet as compared to the cylindrical jet case. This is confirmed by two-dimensional Particle-in-Cell (2D3V PIC) simulations, which demonstrate that the planar jet proves favorable as its geometry leads to more optimized acceleration conditions