Data collection for dilute protein solutions via a neutron backscattering spectrometer

Tominaga, Taiki*; Nakagawa, Hiroshi; Sahara, Masae*; Oda, Takashi*; Inoue, Rintaro*; Sugiyama, Masaaki*

Life (Internet), 12(5), p.675_1 - 675_9, 2022/05

https://doi.org/10.3390/life12050675

The background scattering of sample cells suitable for aqueous protein solution samples, conducted with a neutron backscattering spectrometer, was evaluated. It was found that the scattering intensity of an aluminum sample cell coated with boehmite using DO was lower than that of a sample cell coated with regular water (HO). In addition, meticulous attention to cells with small individual weight differences and the positional reproducibility of the sample cell relative to the spectrometer neutron beam position enabled the accurate subtraction of the scattering profiles of the DO buffer and the sample container. Consequently, high quality information on protein dynamics could be extracted from dilute protein solutions.

Corrosion of aluminum-based containers for neutron studies with aqueous samples under low temperatures

Tominaga, Taiki*; Sahara, Masae*; Kawakita, Yukinobu; Nakagawa, Hiroshi; Shimamoto, Naonobu*

JPS Conference Proceedings (Internet), 33, p.011094_1 - 011094_5, 2021/03

BB2019-2098.pdf:5.18MB

https://doi.org/10.7566/JPSCP.33.011094

In quasielastic neutron scattering studies, aluminum or aluminum alloys are frequently employed as sample cells. With the increasing incident-neutron flux, the research area currently continues to expand; thus, obtaining data has become quicker than ever for dilute conditions. One such area is the water-containing systems. In this study, we investigated the effect of temperature on Al and found that even in a low temperature atmosphere, Al corrosion can occur. This was attributed to the different thermal expansion coefficients of Al as a base substrate and Al oxide as a passivating film.

Development of spin-contrast-variation neutron reflectometry for the structural analysis of multilayer films

Kumada, Takayuki; Akutsu, Kazuhiro*; Oishi, Kazuki*; Morikawa, Toshiaki*; Kawamura, Yukihiko*; Sahara, Masae*; Suzuki, Junichi*; Torikai, Naoya*

Journal of Applied Crystallography, 52(5), p.1054 - 1060, 2019/10

AA2018-0116.pdf:0.86MB

https://doi.org/10.1107/S1600576719010616

We developed a technique of spin-contrast-variation neutron reflectometry (SCV-NR). Polarized-neutron reflectivity curves of film samples vary as a function of their proton-polarization P. The P-dependent reflectivity curves of a polystyrene film was precisely reproduced using a common set of structure parameters and the P-dependent neutron scattering length. The reflectivity curve of poly (styrene-block-isoprene) (PSPI) presented a shoulder attributed to holes with the depth corresponding to one period of periodic lamellae on the free surface only at a specific P. In this way, structural information about specific surfaces or interfaces can be obtained by controlling the P.

Development of spin-contrast-variation neutron reflectometry

Kumada, Takayuki; Akutsu, Kazuhiro*; Kawamura, Yukihiko*; Morikawa, Toshiaki*; Sahara, Masae*; Suzuki, Junichi*; Torikai, Naoya*

no journal, , 

We developed a technique of spin-contrast-variation neutron reflectometry (SCV-NR). Polarized-neutron reflectivity curves of a styrene homopolymer film vary as a function of their proton-polarization, P, coherently with what expected when the films are homogeneously polarized. This result ensures that the SCV-NR curves are not deformed by inhomogeneous P in the film, but determine the structures of surfaces and interfaces properly. Conventional unpolarized neutron reflectivity UNR and negatively-polarized SCV-NR curves of poly(styrene-block-isoprene) (PSPI) films are reproduced by the model that the film has a flat free surface, but positively-polarized SCV-NR curves are not. We found from the global fit that the holes with the depth corresponding to one period of periodic lamellae are produced on the free surface of the PSPI films, whose reflection is hidden by strong one from the PSPI-Si interface in the UNR and negatively-polarized SCV-NR curves.

Development of spin contrast variation neutron reflectometry

Kumada, Takayuki; Akutsu, Kazuhiro*; Oishi, Kazuki*; Morikawa, Toshiaki*; Kawamura, Yukihiko*; Sahara, Masae*; Suzuki, Junichi*; Torikai, Naoya*

no journal, , 

Scattering power of neutron against proton remarkably depends on relative direction of these spins. Spin contrast variation (SCV) is a technique to determine structure of composite materials from their polarized neutron scattering profiles that vary as a function of proton polarization. Very recently, we succeeded in the first SCV neutron reflectometry measurement. We determined roughness of two surfaces of a thin-film polymer from the SCV neutron reflection curves. We will use this technique to study structures of multilayered films such as coupling agents (glues) between organic and inorganic materials.