The characterization offer will provide all the tools necessary to characterize the fabricated samples from the intimate atomic structure to the macroscopic physical properties. The available tools range from table top experiments to large scale facilities. The offer is divided into three installations. The first one is dedicated to unveil the atomic structure and the morphology, including far field and near field microscopy, structural characterizations through electrons, X-rays and neutrons. The second installation aims to give access to the electronic band structure and the chemical states, it includes photo emission and spectroscopy in a wide wavelength range from X-ray to far infrared. Finally the third installation concerns the macroscopic characterizations leading to the electrical and magnetic properties ranging from standard transport measurements to determine the electron density and mobility to SQUID and neutron scattering for the magnetization of the sample.
Confocal microscopy is an optical imaging technique that creates a virtual plane or slice, many micrometers deep within the analyzed sample. Compared to conventional microscopy, it provides fine detailed images of higher quality and with more contrast. In addition, virtual 3-D images of the analyzed microstructure can be obtained by this technique when multiple sections are combined and reconstructed by means of a dedicated computer and software.
This technique has the mission of enabling researchers to visualise and to monitor cellular events in real time and in vivo down to the molecular level, enabling prolonged observations that are not possible with classic confocal microscopes and allowing unparalleled detail in soft matter imaging.
AFM is a surface sensitive technique permitting to obtain a microscopic image of the topography of a material surface. Typical lateral image sizes are within a range of only a few Nanometers to several 10 Micrometers, whereas height changes of less than a Nanometer may be resolved. Additional surface properties may be obtained for each point of the scan such as friction force by lateral force imaging and magnetization properties by magnetic force imaging.
STM allows imaging conductive surfaces at the atomic scale. It is possible to characterize the distribution of surface terraces and steps, as well as to determine the atomic arrangement of (ordered) surface (over)structures.
In SEM a beam is scanned over a sample surface while a signal from secondary or back-scattered electrons is recorded. SEM is used to image an area of the sample with nanometric resolution, and also to measure its composition, crystallographic phase distribution and local texture.
In TEM/Scanning TEM (STEM) high energy electrons incident on ultra-thin samples, allow imaging, diffraction, electron energy loss spectroscopy and chemical analysis of solid materials with a spatial resolution on the order of 1-2 Å. Samples must have a thickness of a few tens of nanometres and are prepared in sample preparation laboratory.
SIMS uses a focused, energetic primary ion beam to bombard the surface of the sample of interest. Atoms are sputtered, ionized and accelerated towards a mass spectrometer. SIMS can provide surface mass spectra, images with lateral resolution in the 0.1 to 10 µm range and depth profiles with depth resolution in the 1 to 10 nm range. SIMS can be quantitative when reference samples are used and can achieve ppm or even ppb sensitivity.
Scanning Transmission X-Ray Microscopy (STXM) is a non-invasive x-ray microscopy technique that enables the acquisition of images with elemental, chemical, and magnetic sensitivity. Typical STXM images exhibit a spatial resolution on the order of 10-20 nm, depending on the zone plate employed to focus the x-rays, and a typical lateral image size on the range of 1-100 µm. This technique requires x-ray transparent samples (typically fabricated on thin Si3N4 membranes or supported by TEM grids).
SAXS is a non-destructive and versatile method to study the nanoscale structure of any type of material ranging from new nanocomposites to biological macromolecules. Parameters as averaged particle sizes, shapes and distributions, the materials' porosity and degree of crystallinity as well as electron density maps with nanometer precision can be obtained. Materials can be solid, liquid or even exhibit gaseous-like properties as aerosols.
XRD provides non-destructive information on the structural order of a material. At large scattering angles XRD permits to identify different crystal phases and to quantify lattice distances and crystalline volume fractions. At low angles of incidence the surface roughness of a single crystal and the thickness of a deposition layer can be obtained. At an angle of incidence below the critical angle XRD is highly surface sensitive.
Neutron imaging allows performing radiography and tomography with fields of view ranging from 20 to 100mm. In the case of large objects need to be measured, radiography can be performed with a field of view of 200x400mm². Several types of sample environment can be provided to the users: furnace (up to 200°C), humidity chamber. The large table for the sample holder allows setting up any sample environment provided by the users.
Neutron diffractometers are well adapted to take measurements on powders, poly-crystals, liquids and amorphous materials. These experiments enable to determine: 1) in crystals, the symmetry of the cell and the average position and space occupied by each atom, 2) in disordered systems, pair correlation functions. Thanks to their specific properties, the neutrons can “see” light atoms easily, hydrogen in particular. The choice of the instrument is determined by the general size of the crystal cell parameter and the required resolution.
Neutron reflectivity is dedicated to the study of interfaces. The reflected intensity at grazing angle of a non polarized white neutron beam is measured as a function of wavelength. The variation of reflectivity is linked to the concentration profile perpendicular to the interface. The thickness, composition and roughness of each layer of the profile is determined within the range from 2 to 500nm for thickness and 1 to 20nm for roughness. All type of interfaces might be studied, including air/liquid interfaces.
A voltage and/or a laser pulse is used to field evaporate atoms from the end of a specimen in the form of a sharp tip. By measuring the time-of-flight and the position of the evaporated atoms on a position sensitive detector a 3-D reconstruction of the position and chemical nature of detected atoms is possible. This technique has sub-nm resolution (around 0.1-0.3nm resolution in depth and 0.3-0.5nm laterally) and detection efficiencies as good as 80%.
The cathodoluminescence integrates a scanning electron microscope (SEM) and a light microscope into one tool allowing SEM images and electron beam induced-luminescence images to be acquired at the same time. The analysis of the features in the luminescence spectra allows the characterization of the material properties (charge carrier recombination, electronic transition) and the detection of defects or impurities.
Thin film reflectometry is a fast and easy technique used to measure the thickness of thin transparent and semi-transparent films on transparent and absorbing substrates. It covers a broad thickness range and can be applied to a high variety of material systems due to the large and extensible material library.
XPS is a surface spectroscopic technique for quantitative measurements of the elemental composition or stoichiometry and the chemical state of the present elements, like their oxidation state and chemical bonds. Due to the limited free path-length of the excited photoelectrons within the material, XPS is highly surface sensitive, giving chemical and binding energy information from the a narrow region close to the surface.
XAS is sensitive to the local bonding environment of the atom absorbing the X-rays, providing information on oxidation states, local orbital symmetry, molecular orientation and chemically selective density of states. It is widely used in molecular and condensed matter physics, material science, engineering, chemistry, earth science and biology.
Photoemission microscopy combines XPS with high spatial resolution, achieved by a small spot X-ray beam or by a magnifying electron optical column. Surface-sensitive images are provided for investigating processes occurring at morphologically/chemically complex solid surfaces including chemical reactions and mass transport processes leading to lateral changes in the composition, morphology and electronic properties of materials.
ARPES allows to measure directly the electronic band structure of crystalline solids. Electrons are detected retrieving information about initial state energy, momentum and spin.
Valence photoemission performed in resonance with core photo-ionization allows to study charge transfers between adsorbate species and the substrate surface and their time scale. If polarisation and emission angles are taken into account, specific atomic sites/bonds of complex molecules are probed. The technique is useful in applications where electron-hole creation and transport phenomena are involved.
Auger Electron Spectroscopy (AES) and SAM are electron beam techniques allowing the analysis of the surface elemental composition of materials. By pointing or scanning the electron beam, localized information or spatial elemental distributions can be obtained. Auger depth profiling allows measuring elemental concentration profiles. In-depth information can also be obtained by analysing a cross-sectional sample.
IR spectroscopy is based on the absorption of infrared radiation by matter. This leads to energetic transitions in the vibrational state of concrete chemical bonds. Since the frequencies that are absorbed by the molecules are characteristic of their structure, this technique is a powerful tool for qualitative molecular analysis, although it can also be used quantitatively.
Raman spectroscopy investigates the vibrational properties of a sample and provides chemical as well as structural information (for example, chemical composition, molecular arrangement or the crystalline structure). Raman spectroscopy does not require any specific sample preparation, size or condition and may be combined with micron spatial resolution when operated using a confocal microscope, and nanometric resolution when operated in TERS or SNOM configuration.
UV/Vis/NIR spectroscopy is the measurement of the attenuation of a beam of light after it passes through a sample or after reflection from a sample surface. It is useful to characterize the absorption, transmission, and reflectivity of a variety of technologically important materials, such as pigments, coatings, windows, and filters.
PL is a non-contact, non-destructive method of probing the electronic structure of materials, often used in the context of semiconductor devices to determine the bandgap energy, the composition of heterostructures, the impurity levels, the crystal quality, and to investigate recombination mechanisms.
Ellipsometry is a contact-free, nondestructive method for characterization of the dielectric and optical properties (refractive index, absorption and thickness) of layered nanostructures in the size range of < 1 nm to several μm.
The pump-probe spectroscopy infrastructure provides in-situ probes of the excited state of the matter, i.e. in the time/frequency domain at the fs-ps scales.
Soft X-rays XAS operating at Ambient Pressure allows for in-operando (under working condition sample environment) spectroscopic investigation of surfaces and their catalytical properties. This opens interesting access to L and M-edges of most of the transition metals and K-edges of light elements (C, O and N). The high surface sensitivity is achieved by the total electron yield detection.
Inelastic X-ray scattering (IXS) permits to analyse several aspects of the dynamics of materials. The techniques involved include Compton scattering, X-ray Raman scattering, and resonant inelastic scattering. In this way electron momentum densities and atomic bonding can be probed and also magnetic excitations or electronic localised or collective states and electronic band-structures.
The facility allows magneto-transport characterizations of semiconductor and metallic samples at temperatures down to liquid helium and fields up to 7T. Density and mobility of carriers can be measured through Hall effect, as well as quantum transport phenomena in 2D systems at low T. Carrier populations can be tuned by bias voltages and external illumination.
The facility provides modular experimental stations to study the evolution of electric and magnetic dipole orders, as well as their degree of coupling, which is an identifying feature of novel magneto-electric systems. The users may assess technologically appealing materials’ features for designing multifunctional devices, such as magneto-electric sensors or high-capacity four-state logic memories.
With MNR is possible to investigate thin magnetic layered structures down to thicknesses between 3–300 Å and lateral structures from nm to µm. The reflection of polarised neutrons allows to determine the density and the modulus and the direction of the magnetisation vector of buried layers. Magnetic roughness, magnetic domains, lateral structures, density profiles, structures of solid polymer layers, etc. are investigated.
When X-ray absorption is measured with circularly/linearly polarized x-rays, spin and angular momenta contributing to the net magnetization / orientation of the magnetization axis, can be determined in ferromagnetic / antiferromagnetic systems, respectively. Dichroic effects arise by the difference between spectra measured with different helicity (left and right circular polarization) / polarization orientation of the X-ray photons.