When beauty is only skin deep; optimizing the sensitivity of specular neutron reflectivity for probing structure beneath the surface of thin films

Abstract

Electrochemical cell for neutron reflectometry studies of the structure of ionic liquids at electrified interface Rev. Sci. Instrum. 81, 074101 (2010) Surface force confinement cell for neutron reflectometry studies of complex fluids under nanoconfinement Rev. Sci. Instrum. 79, 103908 (2008) Millisecond time resolution neutron reflection from a nematic liquid crystal Rev. Sci. Instrum. 75, 2955(2004 Adsorption from alkane+perfluoroalkane mixtures at fluorophobic and fluorophilic surfaces. I. Nature of the noncritical adsorption profiles J. Chem. Phys. 119, 11917 (2003) Local membrane ordering of sponge phases at a solid-solution interface J. Chem. Phys. 116, 8533 (2002) Additional information on J. Appl. Phys. Specular neutron reflectometry has become an established probe of the nanometer scale structure of materials in thin film and multilayered form. It has contributed especially to our understanding of soft condensed matter of interest in polymer science, organic chemistry, and biology and of magnetic hard condensed matter systems. In this paper we examine a number of key factors which have emerged that can limit the sensitivity of neutron reflection as such a probe. Among these is loss of phase information, and we discuss how knowledge about material surrounding a film of interest can be applied to help resolve the problem. In this context we also consider what role the quantum phenomenon of interaction-free measurement might play in enhancing the statistical efficiency for obtaining reflectivity or transmission data.

Surface and interfacial segregation of polyethersulfone deuterated chain ends determined by neutron reflectivity

“…Representative QNM mode AFM height, DMT modulus (E DMT ), and adhesion (F adh ) images of PDP-PESU1 are shown in Figure 3(a), and the nanomechanical properties are summarized in Table 2. PDP-PESU1 shows the highest surface roughness of the three molecular weight species, which was also evidenced in NR experiments (i.e., off-specular reflection 24 ). It is well known that the surface morphology of spin coated films is dependent on properties of the polymer solution as well as the spin coating conditions.…”

Zooming in on disordered systems: Neutron reflection studies of proteins associated with fluid membranes

“…Current structural studies of lipid bilayer membranes and associated proteins with NR require the preparation of the biological interface on solid supports that are flat and atomically smooth over a large area (tens of cm 2 ) [27]. This excludes investigations of natural membranes in vivo but can be readily achieved with artificial membrane systems.…”

“…stBLMs exhibit low interfacial roughness, because of their proximity to the substrate (≈ 20 Å). From a scattering point of view, this is important for achieving high resolution of the underlying structures [27]. On the other hand, the proximity of the substrate to the membrane and interference with the tethering chemistry – typically a molar fraction of 50% of the lipids located in the inner lipid leaflet are tether lipids – may limit the reconstitution of membrane proteins with large extramembraneous domains.…”

Membrane association of the PTEN tumor suppressor: Neutron scattering and MD simulations reveal the structure of protein–membrane complexes

“…Therefore, improvements of data quality are achieved through the reduction of the background by eliminating dispensable sources of scattering. In addition, the signal amplitude can be increased by minimizing the interfacial roughness of the supporting substrate, and consequentially, of the interfacial molecular architecture [66]. At the NIST Center for Neutron Research (NCNR), a background-optimized sample flow cell [67] that exposes a 100 μm thin aqueous reservoir to the neutron beam is used to minimize background.…”