A1 - introduction

• experimental technique used to probe into the nanoscale
• typically beam of x-ray (SAXS)/neutrons (SANS) scattered by a sample, and the intensity of the beam downstream is measured as a function of the angle
• detectors are generally far away from the sample to resolve small angles, hence generally large instruments
• for x-rays, electrons are accelerated by an incoming beam, and a secondary EM wave of identical frequency is emitted
• for neutrons, strong interaction causes QM effects, which can be though of as a source of secondary wavefunction
• physics is different but geometry is identical - huygens-like description
• applicable in chemistry physics, biology and materials science but relatively unpopular due to its reputation as a very indirect technique

image: CJ Gommes, S Jakschb and S Frielinghausb (2021)