BEAR

Welcome to the BEAR beamline  

The beamline operates in the 2.8-1600 eV (443-0.775 nm) spectral region, delivering polarized light of selectable ellipticity -  from nearly linear to elliptical.
The available spectroscopic tools include:
  • Specular (reflectivity) and diffuse light scattering;
  • Soft X-ray excited fluorescence;
  • Soft X-ray excited Auger;
  • X-ray Excited Luminescence (XEOL);
  • Optical absorption measurements  by transmission and particles yield (Total Electron Yield – TEY, Partial Electron Yield – PEY , luminescence and      fluorescence yield, Auger Electrons Yield -AEY);
  • NEXAFS (Near Edge Fine Structure), EXAFS (Extended X-ray Fine Structure);
  • Ultraviolet and X-ray photoemission spectroscopy (UPS-XPS).

Research Highlights

Interface Functionalities in Multilayer Stack Organic Light Emitting Transistors (OLETs)

A multidisciplinary approach to understand the limitations of small molecule organic light emitting transistor here is described. The results showed a mean preferential alignment of the top semiconducting material (DH4T molecules) with the long axis perpendicular to the substrate, with a negligible change by 7° in the DH4T orientation between the heterojunction and the single layer benchmark configuration. This molecular organization is optimal for field-effect transport purposes. R. Capelli  et al., Advanced Functional Materials, 24, 35 (2014).

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Soft x reflectivity of organic films

Polarized resonant soft x ray reflectivity was taken at the carbon K-edge of a self assembled organic film of 1,4-benzenedimethanethiol (BDMT) molecules deposited on gold. The measured reflectivity was simulated by a parameterized phenomenological model, which was fitted to the experimental lineshape. The organic film was treated as an anisotropic material, described by a dielectric tensor with elements obtained from the anisotropic absorption cross section of the molecules, calculated through density functional theory (DFT). L. Pasquali et al., Physical Review B. 89, 045401 (2014)
  

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Pushing the high energy limits of plasmonics

We studied the plasmonic response of oxide-free Al nanoparticles, arranged in densely-packed 2-dimensional arrays on the surface of insulating LiF crystals. The NPs exhibit a broadband plasmonic response in the deep-ultraviolet region of the EM spectrum, peaking at an energy of 6.8 eV, the highest ever reported for a LSP resonance observed by optical excitation of metallic nanoparticles. F. Bisio et al, ACS Nano, 8,9, 9239-9247 (2014)

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Binding Modes, Orientation, and Work Function of ZnO(0001)–Zn surface modified with phosphonate-Based SAM

Two partially fluorinated phosphonates, an alkyl and an aromatic phosphonate, were used to modify the surface work function of ZnO(0001)–Zn single crystals. The unmodified and PA-modified ZnO surfaces were studied by contact angle, SFM, high-resolution XPS, UPS, and XAS. M. Timpel et al, Chemistry of materials, 26, 17, 5042-5050 (2014)

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Silver nanoparticles on nanopatterned LiF(110) surface studied by extreme ultraviolet light scattering

Elastic light scattering was applied to the study of morphology of a periodic nanometric system consisting of a periodic nanopatterned LiF(110) surface functionalized by Ag nanoparticles. The light scattering study was complemented with information from atomic force microscopy. A. Giglia  et al., Journal of Applied Physics 118, 235302 (2015)

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User Area

Proposal Submission

Users are warmly invited to discuss their proposals with the beamline staff, possibly well before the submission deadline. This is crucial for a careful assessment of the experiment feasibility and it generally leads to improvements of the experimental plan. Scientific collaboration with the beamline staff is not necessarily requested. Same rule applies with authorships. The access to beamline on the basis of an approved proposal gives right to routine assistance by the staff. However beamline staff are available for scientific and technical collaboration, to be discussed case-by-case with the responsible, related to scientific issues or instrumental upgradation  of beamline instrumentation in connection with specific experimental requests. For more info, please visit the user info section.

Call for proposals

The deadline for proposal submission for beamtime allocation from January 1st to June 30th, 2017 will be September 15th, 2016.

 

Last Updated on Thursday, 26 May 2016 11:32