The 40 m general purpose small-angle neutron scattering instrument at Oak Ridge National Laboratory

Wignall, G. D.; Littrell, Kenneth C.; Heller, William T.; Melnichenko, Yuri B.; Bailey, Kathy; Lynn, Gary W.; Myles, Dean A. A.; Urban, Volker S.; Buchanan, Michelle V.; Selby, D.L.; Butler, Paul

doi:10.1107/s0021889812027057

Cited by 93 publications

(63 citation statements)

References 31 publications

(31 reference statements)

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“…Polymer size.-Next, we describe our SANS measurements for d-PEG-Ficoll70 solutions (carried out at the High Flux Isotope Reactor at Oak Ridge National Laboratories on the GP-SANS instrument [36]) for PEG concentrations between 0.001 and 0.03 g=cm 3 and Ficoll70 volume fractions between 0 and 0.3. In contrast with PFG NMR, measurements at lower polymer concentrations were impractical due to long acquisition times.…”

Section: Prl 118 097801 (2017) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

Combining Diffusion NMR and Small-Angle Neutron Scattering Enables Precise Measurements of Polymer Chain Compression in a Crowded Environment

Palit

Hamilton

et al. 2017

Phys. Rev. Lett.

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The effect of particles on the behavior of polymers in solution is important in a number of important phenomena such as the effect of "crowding" proteins in cells, colloid-polymer mixtures, and nanoparticle "fillers" in polymer solutions and melts. In this Letter, we study the effect of spherical inert nanoparticles (which we refer to as "crowders") on the diffusion coefficient and radius of gyration of polymers in solution using pulsed-field-gradient NMR and small-angle neutron scattering (SANS), respectively. The diffusion coefficients exhibit a plateau below a characteristic polymer concentration, which we identify as the overlap threshold concentration c ⋆ . Above c ⋆ , in a crossover region between the dilute and semidilute regimes, the (long-time) self-diffusion coefficients are found, universally, to decrease exponentially with polymer concentration at all crowder packing fractions, consistent with a structural basis for the long-time dynamics. The radius of gyration obtained from SANS in the crossover regime changes linearly with an increase in polymer concentration, and must be extrapolated to c ⋆ in order to obtain the radius of gyration of an individual polymer chain. When the polymer radius of gyration and crowder size are comparable, the polymer size is very weakly affected by the presence of crowders, consistent with recent computer simulations. There is significant chain compression, however, when the crowder size is much smaller than the polymer radius gyration.

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Section: Prl 118 097801 (2017) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

Combining Diffusion NMR and Small-Angle Neutron Scattering Enables Precise Measurements of Polymer Chain Compression in a Crowded Environment

Palit

Hamilton

et al. 2017

Phys. Rev. Lett.

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“…SANS experiments were conducted at ORNL on the General Purpose SANS instrument [50] with a neutron wavelength of λ ¼ 4:8Å Δλ=λ $ 0:13 ð Þ . Sample-detector distance was chosen to cover an overall range of scattering vectors (Q) 0.0086 < Q Å À1 , where Q ¼ 4πλ À1 sinθ, in which 2θ is the scattering angle.…”

Section: Porous Fractal Silicamentioning

confidence: 99%

“…In situ SANS measurements were conducted at the GP SANS instrument of the High Flux Isotope Reactor, at ORNL [50] with a neutron wavelength of 4.72 Å (Δλ/λ $ 0.13). The sample-to-distance was chosen to cover an overall range of scattering vectors 0.005 < Q < 0.65 Å À1 .…”

Section: Hydrogen Storage In Activated Carbonsmentioning

confidence: 99%

Supercritical Fluids in Confined Geometries

Melnichenko

2016

Small-Angle Scattering From Confined and Interfacial Fluids

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Understanding the influence of confinement on the structure and thermodynamic properties of supercritical fluids in pores of different surface chemistry and topology is fundamental to the successful development and optimization of the variety of technologies involving fluid-solid interactions. Adsorption behavior of supercritical fluids (SCFs) is fundamentally different from that of subcritical vapors and this chapter begins with a general description of the specifics of the supercritical adsorption. Presented examples illustrate the capability of SAS methods to deliver unique, pore-size-dependent information on the properties of supercritical CO 2 , hydrogen, methane, and other fluids confined in pores of different engineered and natural porous solids. Applications of SAS for studying pore interconnectivity and structural stability of porous materials under pressure are also discussed.

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“…In order to mitigate this count-rate limitation on the GP-SANS (Wignall et al, 2012) and Bio-SANS (Lynn et al, 2006) instruments at the High Flux Isotope Reactor (HFIR) of Oak Ridge National Laboratory (ORNL), the crossed-wire position-sensitive detectors have been replaced by linear position-sensitive detectors (LPSD) arrays (Berry et al, 2012). Other neutron scattering facilities have also implemented LPSD detector arrays for low-q and intermediate-q instruments (Otomo T. et al, 1999, Thiyagarajan, P. et al, 1998.…”

Section: Introductionmentioning

confidence: 99%

“…The measurements were performed on GP-SANS instrument at HFIR (Wignall et al, 2012). The neutron wavelength, λ, was 4.7 Å, while the wavelength spread, ∆λ/λ, was set to 0.13 using the velocity selector.…”

Section: Introductionmentioning

confidence: 99%

Corrections for the geometric distortion of the tube detectors on SANS instruments at ORNL

Qian

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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The small-angle neutron scattering instruments at the Oak Ridge National Laboratory's High Flux Isotope Reactor recently upgraded the area detectors from the large, single volume crossed-wire detectors originally installed to staggered arrays of linear position-sensitive detectors (LPSDs), based on the design used on the EQ-SANS instrument at ORNL's Spallation Neutron Source. The specific geometry of the LPSD array requires that approaches to data reduction traditionally employed be modified.Here, two methods for correcting the geometric distortion produced by the LPSD array are presented and compared. The first method applies a correction derived from a detector sensitivity measurement performed using the same configuration as the samples are measured. In the second method presented here, a solid angle correction derived for the LPSDs is applied to data collected in any instrument configuration during the data reduction process in conjunction with a detector sensitivity 2 measurement collected at a sufficiently long camera length where the geometric distortions are negligible. Both methods produce consistent results and yield a maximum deviation of corrected data from isotropic scattering samples of less than 5% for momentum transfers up to a maximum of 0.8 Å -1 . The results are broadly applicable to any SANS instrument employing LPSD array detectors, which will be increasingly common as instruments having higher incident flux are constructed at various neutron scattering facilities around the world.

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The 40 m general purpose small-angle neutron scattering instrument at Oak Ridge National Laboratory

Cited by 93 publications

References 31 publications

Combining Diffusion NMR and Small-Angle Neutron Scattering Enables Precise Measurements of Polymer Chain Compression in a Crowded Environment

Combining Diffusion NMR and Small-Angle Neutron Scattering Enables Precise Measurements of Polymer Chain Compression in a Crowded Environment

Supercritical Fluids in Confined Geometries

Corrections for the geometric distortion of the tube detectors on SANS instruments at ORNL

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