Coherent amplification of X-ray scattering from meso-structures


Lhermitte, J.R.; Stein, A.; Tian, C.; Zhang, Y.; Wiegart, L.; Fluerasu, A.; Gang, O.; Yager, K.G. "Coherent amplification of X-ray scattering from meso-structures" IUCrJ 2017, 4 604–613.
doi: 10.1107/S2052252517008107


We develop a new method for measuring the x-ray scattering signal from weakly scattering entities that are obscured by a strong background. In particular, we coherently interfere the sample with a specially-designed (strongly-scattering) amplifier. We show that even in cases where the sample itself is unmeasurable, the interference can be detected. Thus, sample scattering is 'boosted' by using the amplifier.


Small-angle X-ray scattering (SAXS) often includes an unwanted background, which increases the required measurement time to resolve the sample structure. This is undesirable in all experiments, and may make measurement of dynamic or radiation-sensitive samples impossible. Here, we demonstrate a new technique, applicable when the scattering signal is background-dominated, which reduces the requisite exposure time. Our method consists of exploiting coherent interference between a sample with a designed strongly scattering `amplifier'. A modified angular correlation function is used to extract the symmetry of the interference term; that is, the scattering arising from the interference between the amplifier and the sample. This enables reconstruction of the sample's symmetry, despite the sample scattering itself being well below the intensity of background scattering. Thus, coherent amplification is used to generate a strong scattering term (well above background), from which sample scattering is inferred. We validate this method using lithographically defined test samples.