ROG
The ROG neutron reflectometer measures the way neutrons are reflected by flat surfaces and interfaces with the aim to provide information about the thickness, composition and roughness of thin films and other layered structures. It can be used to study (stacks of) layers with thicknesses of 5 - 150 nm while providing a resolution up to 0.2 nm. Neutron reflectometry can be used to non-destructively study both liquid and solid samples in a variety of different experimental conditions.
The neutron reflectometer is available to scientist with and without experience with neutron reflectometry from all over the world. Interested? Please contact the instrument scientist to learn more about the possibilities.
The ROG neutron reflectometer is currently being upgraded as part of the OYSTER project. In combination with the installation of a cold neutron source, this will increase its performance by up to 100x.
Applications
- The study of surfaces and interfaces of thin films, multilayers and coatings:
e.g. in-situ determination of hydrogen concentration in metal hydrides, in-operando study of battery materials, composition of thin films of polymers. - Solid-liquid interfaces and membranes: e.g. protein diffusion in membranes, membranes for fuel cells, surfactants, polymers, proteins and enzymes at interfaces, drug delivery systems, study of the interface between a battery electrode and a liquid electrolyte.
- Liquid-air and liquid-liquid interfaces: e.g. proteins, polymers and enzymes in solution,
Example: Thin film metal hydrides as optical hydrogen sensor
The detection of hydrogen is crucial in many industrial processes and for its adaptation as an energy carrier. Thin film metal hydrides can be used to optically probe the hydrogen pressure without the need for electric currents near the sensing area. These sensors utilize the fact that the optical properties change when the hydrogenation of a thin film metal hydride changes in response to a different partial hydrogen pressure in the environment of the sensor. In order to fundamentally understand the structural response of these thin films to hydrogen, facilitating the rational design of new hydrogen sensors, neutron reflectometry was used to study the temperature and hydrogen pressure dependence of the hydrogen content and thickness of the sensing layer in a variety of thin film metal hydrides (e.g. Hf, Ta, Pd1-yAuy). Neutron reflectometry provided the hydrogen pressure dependence of the hydrogen content in the metal hydride layer as well as the volumetric expansion upon hydrogen sorption and thus enabled a deeper and more fundamental understanding of these materials.
Specifications of the instrument
The ROG neutron reflectometer is an unpolarized time-of-flight neutron reflectometer with a horizontal scattering geometry that can be used to study both liquid and solid samples in a variety of different experimental conditions. Further specifications of the reflectometer can be found in the table below.
Specifications of the ROG neutron reflectometer
| |
Chopper and resolution | Double-disk chopper with variable interdisk-distance (0.2-0.7 m) that can operate at 10 – 25 Hz. Typical operation with an interdisk distance of 0.3 m results in Δλ/λ ≈ ΔQ/Q ≈ 0.04 |
Beam size at sample position | 40 mm (width) |
Sample table | +/- 150 mrad, +/- 5 mm vertical displacement, maximum weight of 150 kg |
Wavelength range | 0.3 < λ < 1.5 nm (Cold source, expected) |
Detector | 3He detector |
Sample-to-detector distance | 2 m |
Chopper-to-sample distance | 5 m |
Incident angle
| Solids: -25 < θ < 75 mrad Liquids: 0 < θ < 75 mrad |
Wavevector transfer
| Solids: 0 < Q < 3 nm-1 Liquids: 0 < Q < 3 nm-1 |