Search results for " Reflectivity"
showing 6 items of 26 documents
Correction: Surface induced smectic order in ionic liquids – an X-ray reflectivity study of [C22C1im]+[NTf2]−
2018
Physical chemistry, chemical physics 20(37), 24494 - 24495 (2018). doi:10.1039/C8CP91851A
Surface properties of valine-gramicidin A at the air-water interface
1996
Abstract Fluorescence microscopy, X-ray reflectivity and ellipsometry have been applied to the study of a monolayer of valine-gramicidin A (VGA) at the air-water interface to obtain insight into the conformation and orientation of VGA, and to clarify the shoulder observed in its π - A curve (12.5–16 mN m −1 , 240 – 175 A 2 molecule −1 ). At low molecular areas, the X-ray reflectivities are consistent with formation of a single layer of tubular-shaped dimers. Fluorescence microscopy yielded homogeneous pictures suggesting that on the macroscopic scale the shoulder cannot be attributed to domain formation. Thicknesses calculated from the ellipsometric isotherm are consistent with the X-ray da…
Structural Characterization of Molecular Interface Layers Using Neutron and X-Ray Reflectivity Techniques
1992
Synthetic microstructures used in biological research today include a variety of different systems that serve very diverse purposes and require very different fabrication and characterization techniques. One class of microstructures that is at the boundary between life and materials sciences, and certainly has been associated closer to the latter in the past, is that of molecularly structured planar interface films. In fact, Langmuir-Blodgett (LB) films,1 i.e. molecularly layered films comprised of amphiphatic organic molecules on solid substrates, have been used for many years as model systems for the investigation of molecular interactions between chromophores or donor/ acceptor couples, …
Study on the initial stages of water corrosion of fluorozirconate glasses
2004
Abstract The surface corrosion process associated with the hydrolysis of fluorozirconate glass, ZBLAN (53ZrF 4 , 20BaF 2 , 20NaF, 4LaF 2 , 3AlF 3 ) was investigated using X-ray photoelectron spectroscopy (XPS), grazing-incidence small angle X-ray scattering (GISAXS), X-ray reflectivity (XRR) and scanning electron microscopy (SEM). After a short exposure period (25 min) of the glass surface to deionized water the XPS data indicate an increase of the oxygen content accompanied by a decrease of fluorine concentration. The analysis of the chemical bonding structure identified the predominant surface reaction products as zirconium hydroxyfluoride and oxyfluoride species. The second most abundant…
Properties of Hydrophobic Polymer Melts Tethered to the Water Surface As Determined with in Situ X-ray Reflectivity
1997
Insoluble monolayers of hydrophobic polymers with low glass transition temperature (perfluoropolyethers, polyisoprenes) and a single ionic head group (carboxylic acid, sulfonate) have been characterized at the air/water interface via X-ray reflectivity measurements. The films are considerably thicker (30−420 A) than conventional Langmuir monolayers of low molecular weight substances or polymers with surface active repeat units. The thickness is inversely proportional to the area per head group and is in accordance with a model assuming a solvent-free hydrophobic layer of the same density as the bulk material.
Unravelling the Intertwined Atomic and Bulk Nature of Localised Excitons by Attosecond Spectroscopy
2021
The electro-optical properties of most semiconductors and insulators of technological interest are dominated by the presence of electron-hole quasi-particles, called excitons. The manipulation of excitons in dielectrics has recently received great attention, with possible applications in different fields including optoelectronics and photonics. Here, we apply attosecond transient reflection spectroscopy in a sequential two-foci geometry and observe sub-femtosecond dynamics of a core-level exciton in bulk MgF2 single crystals. Furthermore, we access absolute phase delays, which allow for an unambiguous comparison with theoretical calculations. Our results show that excitons surprisingly exhi…