FEMTOSPEX Molecules and Surfaces: Electron spectroscopy setup for time-resolved laser-pump/ X-ray-probe experiments at BESSY II

Sorgenfrei, F.

doi:10.17815/jlsrf-2-87

Cited by 2 publications

(2 citation statements)

References 2 publications

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“…All experimental data presented in this work have been acquired, at the “FEMTOSPEX Molecules and Surfaces” endstation 41 , installed at the BESSY II soft X-ray UE56/1 PGM beamline during the single bunch operation mode. The beamline provides adjustable X-ray polarizations (linear vertical and horizontal as well as circular) with a focus spot size on the sample of approximately 200 x 200 .…”

Section: Methodsmentioning

confidence: 99%

Directional charge delocalization dynamics in semiconducting 2H-MoS$$_{2}$$ and metallic 1T-Li$$_{\mathrm{x}}$$MoS$$_{2}$$

Haverkamp

Sorgenfrei

Giangrisostomi

et al. 2021

Sci Rep

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The layered dichalcogenide MoS$$_{2}$$ 2 is relevant for electrochemical Li adsorption/intercalation, in the course of which the material undergoes a concomitant structural phase transition from semiconducting 2H-MoS$$_{2}$$ 2 to metallic 1T-Li$$_{\mathrm{x}}$$ x MoS$$_{2}$$ 2 . With the core hole clock approach at the S L$$_{1}$$ 1 X-ray absorption edge we quantify the ultrafast directional charge transfer of excited S3p electrons in-plane ($$\parallel$$ ‖ ) and out-of-plane ($$\perp$$ ⊥ ) for 2H-MoS$$_{2}$$ 2 as $$\tau _{2H,\parallel } = 0.38 \pm 0.08$$ τ 2 H , ‖ = 0.38 ± 0.08 fs and $$\tau _{2H,\perp } = 0.33 \pm 0.06$$ τ 2 H , ⊥ = 0.33 ± 0.06 fs and for 1T-Li$$_{\mathrm{x}}$$ x MoS$$_{2}$$ 2 as $$\tau _{1T,\parallel } = 0.32 \pm 0.12$$ τ 1 T , ‖ = 0.32 ± 0.12 fs and $$\tau _{1T,\perp } = 0.09 \pm 0.07$$ τ 1 T , ⊥ = 0.09 ± 0.07 fs. The isotropic charge delocalization of S3p electrons in the semiconducting 2H phase within the S-Mo-S sheets is assigned to the specific symmetry of the Mo-S bonding arrangement. Formation of 1T-Li$$_{\mathrm{x}}$$ x MoS$$_{2}$$ 2 by lithiation accelerates the in-plane charge transfer by a factor of $$\sim 1.2$$ ∼ 1.2 due to electron injection to the Mo-S covalent bonds and concomitant structural repositioning of S atoms within the S-Mo-S sheets. For excitation into out-of-plane orbitals, an accelerated charge transfer by a factor of $$\sim 3.7$$ ∼ 3.7 upon lithiation occurs due to S-Li coupling.

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Section: Methodsmentioning

confidence: 99%

Directional charge delocalization dynamics in semiconducting 2H-MoS$$_{2}$$ and metallic 1T-Li$$_{\mathrm{x}}$$MoS$$_{2}$$

Haverkamp

Sorgenfrei

Giangrisostomi

et al. 2021

Sci Rep

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“…■ METHODS XPS Measurements. All experimental data presented in this work have been acquired at the "FEMTOSPEX Molecules and Surfaces" endstation, 34 installed at the BESSY II soft X-ray UE56/1 PGM beamline during the single-bunch operation mode. The beamline provides adjustable X-ray polarizations (linear, vertical, and horizontal as well as circular) with a focus spot size on the sample of approximately 200 μm × 200 μm.…”

mentioning

confidence: 99%

Near-Isotropic Local Attosecond Charge Transfer within the Anisotropic Puckered Layers of Black Phosphorus

Haverkamp,

Neppl,

Föhlisch

2023

J. Phys. Chem. Lett.

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Black phosphorus possesses useful two-dimensional (2D) characteristics of van der Waals coupled materials but additionally features an in-plane anisotropic puckered layer structure that deviates from common 2D materials. Three distinct directions exist within the lattice of black phosphorus: the in-plane armchair and zigzag directions and the out-of-plane direction, with each distinct phosphorus 3p partial density of states. This structural anisotropy is imprinted onto various collective long-range properties, while the extent to which local electronic processes are governed by this directionality is unclear. At the P L 1 edge, the directional selectivity of the core-hole clock method was used to probe the local charge transfer dynamics of electrons excited into the 3p-derived conduction band on an attosecond time scale. Here we show that the surprisingly small anisotropy of 3p electron transfer times reflects the similarly small differences in the 3p-derived unoccupied density of states caused by the underlying phosphorus bonding angles within the puckered layers.

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FEMTOSPEX Molecules and Surfaces: Electron spectroscopy setup for time-resolved laser-pump/ X-ray-probe experiments at BESSY II

Abstract: The exible end station "FEMTOSPEX Molecules and Surfaces", which will enable time resolved photoemission studies in the future at HZB, is presented.

Cited by 2 publications

References 2 publications

Directional charge delocalization dynamics in semiconducting 2H-MoS$$_{2}$$ and metallic 1T-Li$$_{\mathrm{x}}$$MoS$$_{2}$$

Directional charge delocalization dynamics in semiconducting 2H-MoS$$_{2}$$ and metallic 1T-Li$$_{\mathrm{x}}$$MoS$$_{2}$$

Near-Isotropic Local Attosecond Charge Transfer within the Anisotropic Puckered Layers of Black Phosphorus

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