Measurements of Dynamic Contributions to Coherent Neutron Scattering

Abstract

During this experiment we were testing the hypothesis that standing waves in a phospholipid membrane stack indeed lead to a detectable signal in coherent grazing-incidence small-angle neutron scattering, GISANS. These modes were identified earlier in a previous experiment using grazing-incidence neutron spin-echo spectroscopy, GINSES, (Jaksch, S., Frielinghaus, H. et al. (2017). Nanoscale rheology at solidcomplex fluid interfaces. Scientific Reports, 7(1), 4417.). In order to identify those modes and prove conclusively that they were indeed a dynamic mode of the membrane and not a measurement artifact we were following a predetermined protocol: Starting at a physiological temperature (35 • C), where the modes were previously identified in GINSES, we lowered the temperature of the sample. Dynamic modes as an eigenmode of the lamellar system would under those conditions at least shift the position of any occurring peaks. Possibly below a phase transition temperature (approximately 25 • C for such a layered system) the peaks due to coherent scattering from a standing wave would vanish altogether, as the standing wave cannot be sustained by thermal excitation at that temperature. Upon reheating, any scattering contribution that is purely due to scattering from a standing wave would reappear. All experiments were performed on the MARIA instrument at MLZ.

Using Grazing-Incidence Small-Angle Neutron Scattering to Study the Orientation of Block Copolymer Morphologies in Thin Films

“…GISANS has since been widely used to study micelles − and other nanomaterials near surfaces and interfaces . GISANS has also been used to study phospholipid membranes. − Microphase-separated morphologies of block copolymers were investigated by GISANS with depth sensitivity. , The morphologies near the film interfaces were also selectively probed. − Time-of-flight GISANS allowed scattering at different wavelengths to be collected during one single measurement with a white beam, providing new measurement opportunities. − Besides developing experimental methods, theories and software that allowed background subtraction and quantitative analysis of GISANS data also evolved during the same time. , …”

Influence of NaCl on the Structure and Dynamics of Phospholipid Layers

“…In the case of the latter, the interplay between dynamics and structure is of particular importance. The structure and dynamics of phospholipid membranes has been the subjects of a wide array of investigations ranging from light-scattering [2] and AFM studies [3] over X-ray scattering [4][5][6][7][8][9][10] to elastic [11][12][13] and inelastic neutron scattering [14][15][16][17]. An overview of the interplay between structure and dynamical behavior was published by Tanaka [18], and reviews focusing on neutron and X-ray scattering were published by Rheinstädter and Fragneto [19], and Salditt [8].…”