56 research outputs found
Sailing Close to the Wind: Human Rights Council Fact-Finding in Situations of Armed Conflict -- The Case of Syria
Der Schutz geographischer Herkunftsangaben: Herausforderungen für agrarökonomische, rechtswissenschaftliche und interdisziplinäre Forschung
Agricultural and Food Policy, Marketing,
Opening address at the Colloquium ‘Good Governance in Land Tenure’ held at Potchefstroom on 22 and 23 April 2010: Land Tenure and Good Governance from the perspective of International Law.
Addressing land tenure from the perspective of international law is challenging, not least because there are hardly any legally binding international instruments which explicitly address the issue.
 
Thickness-Dependent Differential Reflectance Spectra of Monolayer and Few-Layer MoS2, MoSe2, WS2 and WSe2
The research field of two dimensional (2D) materials strongly relies on
optical microscopy characterization tools to identify atomically thin materials
and to determine their number of layers. Moreover, optical microscopy-based
techniques opened the door to study the optical properties of these
nanomaterials. We presented a comprehensive study of the differential
reflectance spectra of 2D semiconducting transition metal dichalcogenides
(TMDCs), MoS2, MoSe2, WS2, and WSe2, with thickness ranging from one layer up
to six layers. We analyzed the thickness-dependent energy of the different
excitonic features, indicating the change in the band structure of the
different TMDC materials with the number of layers. Our work provided a route
to employ differential reflectance spectroscopy for determining the number of
layers of MoS2, MoSe2, WS2, and WSe2.Comment: Main text (3 Figures) and Supp. Info. (23 Figures
Nature of the excited states of layered systems and molecular excimers: Exciplex states and their dependence on structure
Pressure dependence of intra- and interlayer excitons in 2H-MoS bilayers
The optical and electronic properties of multilayer transition metal
dichalcogenides differ significantly from their monolayer counterparts due to
interlayer interactions. The separation of individual layers can be tuned in a
controlled way by applying pressure. Here, we use a diamond anvil cell to
compress bilayers of 2H-MoS in the gigapascal range. By measuring optical
transmission spectra, we find that increasing pressure leads to a decrease in
the energy splitting between the A and interlayer exciton. Comparing our
experimental findings with ab initio calculations, we conclude that the
observed changes are not due to the commonly assumed hydrostatic compression.
This effect is attributed to the MoS bilayer adhering to the diamond, which
reduces in-plane compression. Moreover, we demonstrate that the distinct
real-space distributions and resulting contributions from the valence band
account for the different pressure dependencies of the inter- and intralayer
excitons in compressed MoS bilayers.Comment: 8 pages, 5 figure
Interlayer excitons in a bulk van der Waals semiconductor (vol 8, 639, 2017)
A correction to this article has been published and is linked from the HTML version of this article
Thickness-dependent differential reflectance spectra of monolayer and few-layer MoS2, MoSe2, WS2 and WSe2
The research field of two dimensional (2D) materials strongly relies on optical microscopy characterization tools to identify atomically thin materials and to determine their number of layers. Moreover, optical microscopy-based techniques opened the door to study the optical properties of these nanomaterials. We presented a comprehensive study of the differential reflectance spectra of 2D semiconducting transition metal dichalcogenides (TMDCs), MoS2, MoSe2, WS2, and WSe2, with thickness ranging from one layer up to six layers. We analyzed the thickness-dependent energy of the different excitonic features, indicating the change in the band structure of the different TMDC materials with the number of layers. Our work provided a route to employ differential reflectance spectroscopy for determining the number of layers of MoS2, MoSe2, WS2, and WSe2
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