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This lecture is intended for people who want to become independent self-user of the small or wide angle X-ray scattering (SAXS) instrument in the MRL X-Ray Lab.  SAXS describes the analysis of any sample that has nanostructured (1-100nm) electron density fluctuations -- i.e., nanoparticles in solution, block co-polymers, ionic liquids, soft matter, etc. Typically nanoscale electron density variations arise as structured (nanoscale object in a lattice), unstructured (in solution), or oriented (fiber or affixed to substrate) therefore treatment of each type of sample is on a case by case basis.  

Students must also attend SAXSLAB instrument specific training course to learn how to put the knowledge obtained in the lecture to practice.

This lecture will survey the fundamentals of small angle X-ray scattering (SAXS), focusing on the bare essentials required to productively collect and analyze SAXS data.  In addition to theory, this lecture will cover practical considerations such as common sources of error and a guide to structural interpretation and justification using SAXS patterns.

This course will teach users the basics of data collection using the SAXSLAB instrument.  The SAXSLAB system has automated detector positioning for SAXS/WAXS analyses of samples in capillaries or freestanding films in a transmission geometry and GISAXS/GIWAXS of samples supported on a monolithic substrate in grazing incidence reflection gemoetry. Calibration of the q-range using silver behenate, acquisition of empty, buffer (if sample is immersed in solvent) and dark current exposures for similar timescales and data reduction procedures will be covered. The SAXSLAB instrument is very well suited for analyzing polymers, soft materials, nanoparticles in solution or dried on substrates, porous samples, and nanostructured surfaces. The emphasis in this training session will be design of experiment, routine collection and data reduction.

SAXS - small angle X-ray scattering
WAXS - wide angle X-ray scattering
GISAXS - grazing incidence small angle X-ray scattering

Active MIT.nano user account is required to participate in this training. Please setup an account prior to registering for the training event. 

This course is intended to provide users with practical examples of fitting SAXS data with SASview software.

Since most SAXS profiles do not exhibit well defined peaks like crystalline diffraction but instead characteristic "slopes," it is a heavily model-dependent method. After proper data reduction of a SAXS patterns, the data interpretation methods include extracting structural information from standardized plots such as Guinier, Porod, Kratky and Zimm plots. Elements of SAXS data modeling include calculations of the radius of gyration, of the single-particle form factor, inter-particle structure factors and the modeling effects of polydispersity.