Versatile X-ray reflector extension setup for grazing-incidence experiments at SAXS facilities for liquid surface...

Area of Science:

• Materials Science
• Nanotechnology
• X-ray Scattering Physics

Background:

• Existing in situ grazing-incidence small-angle scattering (GISAXS) methods face limitations in angular range and resolution for liquid surface studies.
• Achieving sub-micrometer resolution typically requires large sample-detector distances, which are often incompatible with current beamline setups.

Purpose of the Study:

• To present a low-cost, easily assembled beam-tilting extension for synchrotron-based ultra-small-angle X-ray scattering (USAXS) facilities.
• To enable grazing-incidence ultra-small-angle X-ray scattering (GIUSAXS) and transmitted scattering (GTUSAXS) studies on liquid surfaces with enhanced resolution.

Main Methods:

• Developed a beam-tilting extension compatible with standard USAXS beamlines, requiring minimal additional space (~0.5 m).
• The system allows X-ray beam incidence angles up to ~0.6°, providing access to a q-range of approximately 0.003-0.5 nm⁻¹.
• Tested the setup at the P03 beamline (DESY) using polystyrene nanoparticles (~197 nm) self-assembled at the air/water interface.

Main Results:

• Successfully recorded GIUSAXS and GTUSAXS patterns from polystyrene nanoparticles at the air/water interface.
• Observed features characteristic of near-surface hexagonally ordered monolayers and multilayer assemblies.
• Validated the system's resolution and sensitivity for studying sub-micrometer nanostructured objects.

Conclusions:

• The proposed beam-tilting scheme effectively expands the research capabilities of existing USAXS synchrotron facilities for in situ studies.
• Enables selective depth profiling of nanostructures at liquid surfaces using grazing-incidence geometry.
• The system is fully compatible with complementary techniques like grazing-incidence wide-angle scattering (GIWAXS) and total reflection X-ray fluorescence (TXRF).