Advanced optical characterization of nanostructures and nanomaterials in the X-ray range

Abstract

The electromagnetic radiation has given rise to a number of diagnostics techniques covering a broad range of the wave lengths that are of vital importance for materials science. In particular, their non-destructive character and possibility to perform time-resolved studies under various external conditions (temperature, ambient, electrical and/or magnetic fields, etc.) render these techniques very attractive. Reduction of the typical size of inspected nanoobjects down to nanometers and even below triggered by the development of nanotechnology and nanoscience favours application of the techniques confined to X-ray range, in particular to hard X-rays of the wavelength of the order of 0.1 nm. Here, the grazing-incidence small-angle X-ray scattering (GISAXS) is one of the most important methods allowing to obtain statistically relevant parameters in terms of the position, correlations and size distribution of nanoobjects such as supported nanoparticle as semblies or fractal and correlation properties of the rough surfaces and interfaces. The GISAXS technique probes the nanostructure in a selected part of the reciprocal space defined by the experimental parameters that is projected onto a 2D detector as GISAXS pattern. The GISAXS information is thus complementary to that provided by the real-space investigation methods such electron microscopy or scanning probe techniques which are local by nature. On the other hand, the transformation from the reciprocal to real space and adoption of an appropriate model is necessary for GISAXS. As the GISAXS signal scales with the amount of the probed material and is inherently weak for nanostructures, the X-ray beam flux is an important issue. Recent development of the high-intense liquid-jet Ga X-ray sources has allowed to reach a total flux of 109–1010 ph/sin laboratory. However, the synchrotron radiation is necessary in particular cases.