The core of the technology is the oscillating unit - a thin quartz crystal disk, which has electrodes deposited on each side. Via an applied voltage, the crystal can be excited to resonance, and the resonance frequency is related to the mass of the disk. If the thickness changes, so will the resonance frequency, f. By monitoring changes of the resonance frequency, Δf, it is possible to detect small changes of the crystal mass. The measurement enables the detection of nanoscale mass changes such as adsorption or binding of molecules to the surface, which will be detected as mass increase, whereas mass decrease will indicate mass removal, for example via molecular desorption or etching of the surface. In addition, QCM-D measures the dissipation, ΔD. The dissipation gives information about the energy losses in the system and are particularly useful in the study of soft layers, where this information is used for quantification of the layer properties. Applications:
SAXS is a non-destructive and versatile method to study the nanoscale structure of any type of material (solid, liquid, aerosols) ranging from new nanocomposites to biological macromolecules. Averaged particle sizes, shapes and distributions, porosity, degree of crystallinity and electron density maps with nanometer precision can be obtained.
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 AUC is used to measure the size distribution of nanoparticles and macromolecules in suspension. The instrument performs well in the size distribution measurement of small nanoparticles from proteins and other macromolecules to viruses, liposomes and inorganic submicron particles.
MALS is a technique for measuring light scattered by a sample into a plurality of angles. It is used to determine both the absolute molar mass and the average size of molecules in solution. MALS is typically used as a flow-mode detector coupled to Asymmetric Flow Field Flow fractionation (AF4) or Size Exclusion Chromatography (SEC).