All about SAX you need to know

Small angle X-ray diffraction (SAX) is a powerful technique employed in various scientific fields, particularly in materials science and structural biology, to investigate the nanoscale and mesoscale structures of materials. By utilizing X-rays with wavelengths on the order of atomic spacing, SAXD can provide valuable insights into the arrangement, orientation, and periodicity of atoms and molecules within a sample. This method is particularly useful for studying the structural characteristics of polymers, liquid crystals, colloids, and biological macromolecules such as proteins and nucleic acids. SAXD experiments typically involve analyzing the scattering patterns generated when X-rays interact with the sample, offering detailed information about its internal structure and enabling researchers to understand fundamental properties and behaviors crucial for a wide range of applications, including drug development, materials design, and nanotechnology.

Equipment and Materials:

X-ray source (usually a synchrotron or laboratory X-ray generator)
Sample holder (e.g., capillary, film, or plate)
Detector (e.g., CCD camera or image plate)
Goniometer or sample stage for precise angular positioning
Data analysis software (e.g., Fit2D, Igor Pro, or PyFAI)
Safety equipment (e.g., radiation shielding, goggles)

Protocol:

Sample Preparation: Prepare your sample in the desired form (e.g., solution, film, or powder).

Experimental Setup:
Mount the sample on the sample holder, ensuring it is flat and homogeneous.
Align the X-ray source, sample holder, and detector to the desired geometry (usually perpendicular to the X-ray beam).

Data Collection:
Adjust the X-ray wavelength and intensity according to the sample characteristics.
Scan the sample over the desired angular range while collecting X-ray scattering data.
Collect background and calibration measurements for accurate data analysis.

Data Analysis:
Process the raw data using specialized software to obtain 1D or 2D scattering patterns.
Analyze the scattering patterns to extract information about the sample’s nano/mesoscale structure (e.g., periodicity, orientation).

Interpretation and Reporting:
Interpret the results in the context of the sample’s composition and properties.
Compare with theoretical models or known standards for validation.
Report the findings in scientific publications or presentations.

References:

Glatter, O., & Kratky, O. (1982). Small angle X-ray scattering. Academic Press.
Svergun, D. I. (1992). Determination of the regularization parameter in indirect-transform methods using perceptual criteria. Journal of Applied Crystallography, 25(4), 495-503.
Hammersley, A. P., Svensson, S. O., Hanfland, M., Fitch, A. N., & Hausermann, D. (1996). Two-dimensional detector software: From real detector to idealised image or two-theta scan. High Pressure Research, 14(4-6), 235-248.

Tools and Software:

Fit2D: https://www.esrf.eu/computing/scientific/FIT2D/
Igor Pro: https://www.wavemetrics.com/
PyFAI: https://github.com/silx-kit/pyFAI

These resources provide detailed information on SAXD theory, experimental techniques, and data analysis methods, aiding researchers in conducting and interpreting SAX experiments effectively.