AMOR – the versatile reflectometer at SINQ

Clemens, Daniel; Gross, Patricio; Keller, P.; Schlumpf, N.; Könnecke, Mark

doi:10.1016/s0921-4526(99)01386-1

Cited by 38 publications

(33 citation statements)

References 3 publications

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“…The difference between using neutrons over X-rays is that the neutrons scatter from the atomic nuclei rather than from electrons. The neutron scattering power can vary greatly between neighbouring elements and isotopes of the same element; therefore, NR, unlike XRR, is sensitive to neighbouring light elements (H, C, O, N) and isotopic substitution [27][28][29] and can provide depth profiles with sub-Ångstrom resolution 30 .…”

Section: Resultsmentioning

confidence: 99%

Examining the surface evolution of LaTiOxNy an oxynitride solar water splitting photocatalyst

et al. 2020

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LaTiO x N y oxynitride thin films are employed to study the surface modifications at the solidliquid interface that occur during photoelectrocatalytic water splitting. Neutron reflectometry and grazing incidence x-ray absorption spectroscopy were utilised to distinguish between the surface and bulk signals, with a surface sensitivity of 3 nm. Here we show, contrary to what is typically assumed, that the A cations are active sites that undergo oxidation at the surface as a consequence of the water splitting process. Whereas, the B cations undergo local disordering with the valence state remaining unchanged. This surface modification reduces the overall water splitting efficiency, but is suppressed when the oxynitride thin films are decorated with a co-catalyst. With this example we present the possibilities of surface sensitive studies using techniques capable of operando measurements in water, opening up new opportunities for applications to other materials and for surface sensitive, operando studies of the water splitting process.

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Section: Resultsmentioning

confidence: 99%

Examining the surface evolution of LaTiOxNy an oxynitride solar water splitting photocatalyst

et al. 2020

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“…The layer thickness was determined by SIMS (CAMECA IMS 3 F, 15 kV, 40 nA, O ÿ ). Diffusion annealing was carried out in nitrogen (980 mbar) in the temperature range between 950 and 1250 C. Determination of the nitrogen self-diffusivities was obtained by neutron reflectivity in the time-of-flight mode of the AMOR reflectometer at the Swiss spallation neutron source (SINQ), located at the Paul Scherrer Institute (Switzerland) [8]. At incoming neutron wavelengths, , between 0.2 and 0.9 nm the reflectivity patterns were measured at three different incident angles at 0:3 , 0.7 , and 1.3 .…”

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confidence: 99%

Nitrogen Diffusion in Amorphous Silicon Nitride Isotope Multilayers Probed by Neutron Reflectometry

2006

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Amorphous silicon nitride is a model system for a covalently bound amorphous solid with a low atomic mobility where reasonable values of self-diffusivities are still lacking. We used neutron reflectometry on isotope enriched Si3 14N4/Si3 15N4 multilayers to determine nitrogen self-diffusivities ranging from 10(-24) to 10(-21) m2/s between 950 and 1250 degrees C. Time dependent diffusivities observed at 1150 degrees C indicate the presence of structural relaxation. For long annealing times (relaxed state) the diffusivities follow an Arrhenius law with an activation enthalpy of (3.6 +/- 0.4) eV. The results are indicative of a direct diffusion mechanism without the involvement of thermal point defects.

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“…34,35 Measurements were made at three incident angles (0.61, 1.41 and 2.41), which gave a range of momentum transfer Q (Q = (4p siny)/l, with l being the wavelength and y the angle of incidence) from 0.1 to 1.5 nm À1 . Neutron reflectivity.…”

Section: Ii2 Methodsmentioning

confidence: 99%

Photoswitching the mechanical properties in Langmuir layers of semifluorinated alkyl-azobenzenes at the air–water interface

Theodoratou

Jonas

Loppinet

et al. 2015

Phys. Chem. Chem. Phys.

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Semifluorinated alkyl-azobenzene derivatives (SFAB) can form stable Langmuir layers at the air-water interface. These systems combine the amphiphobic character of semifluorinated alkyl units as structure-directing motifs with photochromic behavior based on the well-known reversible cis-trans isomerization upon irradiation with UV and visible light. Herein, we report our investigations of the structural and dynamic tunability of these SFAB layers at the air-water interface in response to an external light stimulus. The monolayer structures and properties of [4-(heptadecafluorooctyl)phenyl](4-octylphenyl)diazene (F8-azo-H8) and bis(4-octylphenyl)diazene (H8-azo-H8) were studied by neutron reflectivity, surface pressure-area isotherms with compression-expansion cycles, and interfacial rheology. We find that UV irradiation reversibly influences the packing behavior of the azobenzene molecules and interpret this as a transition from organized layer structures with the main axis of the molecule vertically oriented in the trans form to random packing of the cis isomer. Interestingly, this trans-cis isomerization leads to an increase in surface pressure, which is accompanied by a decrease in viscoelastic moduli. These results suggest ways of tailoring the properties of responsive fluid interfaces.

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AMOR – the versatile reflectometer at SINQ

Cited by 38 publications

References 3 publications

Examining the surface evolution of LaTiOxNy an oxynitride solar water splitting photocatalyst

Examining the surface evolution of LaTiOxNy an oxynitride solar water splitting photocatalyst

Nitrogen Diffusion in Amorphous Silicon Nitride Isotope Multilayers Probed by Neutron Reflectometry

Photoswitching the mechanical properties in Langmuir layers of semifluorinated alkyl-azobenzenes at the air–water interface

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