Adapting a triple-axis spectrometer for small angle neutron scattering measurements

Nieh, Mu‐Ping; Yamani, Z.; Kučerka, Norbert; Katsaras, John; Burgess, D.M.; Breton, Hugo

doi:10.1063/1.2969254

Cited by 7 publications

(6 citation statements)

References 15 publications

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“…Furthermore, smearing effects due to vertical divergence from the slit geometry are reduced through the use of horizontal Soller collimators. As a result, this modified triple-axis spectrometer enables SANS measurements to a minimum q value (q min ) of 0.006 Å í1 [1]. Data obtained from the modified triple-axis spectrometer are in good agreement with those data from the 30 m NG3-SANS instrument located at the National Institute of Standards and Technology (Gaithersburg, MD, USA).…”

supporting

confidence: 70%

Adapting a triple-axis spectrometer for small angle neutron scattering measurements

Nieh¹,

Yamani²,

Kučerka³

et al. 2010

J. Phys.: Conf. Ser.

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Abstract. Small angle neutron scattering (SANS) instruments typically require a cold source and a large spread of wavelengths in order to enhance incident flux. However, as a direct result of the unavailability of a cold source at the Canadian Neutron Beam Centre (CNBC), we have resorted to adapting a triple-axis spectrometer for SANS measurements. This is achieved through the use of multiple converging incident beams which enhance the neutron flux on the sample by a factor of 20, compared to a single beam of same spot size. Furthermore, smearing effects due to vertical divergence from the slit geometry are reduced through the use of horizontal Soller collimators. As a result, this modified triple-axis spectrometer enables SANS measurements to a minimum q value (q min ) of 0.006 Å í1 [1]. Data obtained from the modified triple-axis spectrometer are in good agreement with those data from the 30 m NG3-SANS instrument located at the National Institute of Standards and Technology (Gaithersburg, MD, USA).

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supporting

confidence: 70%

Adapting a triple-axis spectrometer for small angle neutron scattering measurements

Nieh¹,

Yamani²,

Kučerka³

et al. 2010

J. Phys.: Conf. Ser.

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“…The incident beam was focused with a multichannel focusing collimator, and a “de-smearing” collimator was installed to reduce the vertical divergence on the scattering side. A detailed description of the optical configuration and instrumental resolution has been previously reported . At CG3, the wavelength was fixed at 6 Å and the sample-to-detector distance was set to 6 m, covering a q range from 0.005 to 0.15 Å –1 .…”

Section: Methodsmentioning

confidence: 99%

“…A detailed description of the optical configuration and instrumental resolution has been previously reported. 35 At CG3, the wavelength was fixed at 6 Å and the sample-todetector distance was set to 6 m, covering a q range from 0.005 to 0.15 Å −1 . The temperature of the sample stage, at both facilities, was controlled by a circulating water bath.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Morphological Characterization of DMPC/CHAPSO Bicellar Mixtures: A Combined SANS and NMR Study

Morales

Katsaras

et al. 2013

Langmuir

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Spontaneously forming structures of a system composed of dimyristoyl phosphatidylcholine (DMPC) and 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulfonate (CHAPSO) were studied by small-angle neutron scattering (SANS), (31)P NMR, and stimulated echo (STE) pulsed field gradient (PFG) (1)H NMR diffusion measurements. Charged lipid dimyristoyl phosphatidylglycerol (DMPG) was used to induce different surface charge densities. The structures adopted were investigated as a function of temperature and lipid concentration for samples with a constant molar ratio of long-chain to short-chain lipids (= 3). In the absence of DMPG, zwitterionic bicellar mixtures exhibited a phase transition from discoidal bicelles, or ribbons, to multilamellar vesicles either upon dilution or with increased temperature. CHAPSO-containing mixtures showed a higher thermal stability in morphology than DHPC-containing mixtures at the corresponding lipid concentrations. In the presence of DMPG, discoidal bicelles (or ribbons) were also found at low temperature and lower lipid concentration mixtures. At high temperature, perforated lamellae were observed in high-concentration mixtures (≥7.5 wt %) whereas uniform unilamellar vesicles and bicelles formed in low-concentration mixtures (≤2.5 wt %), respectively, when the mixtures were moderately and highly charged. From the results, spontaneous structural diagrams of the zwitterionic and charged systems were constructed.

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“…Small-angle neutron scattering measurements were conducted on the recently modified N5 spectrometer located at the National Research Universal (NRU) reactor (Chalk River, Ontario, Canada) . Neutrons of 2.37 Å were chosen using a pyrolytic graphite (PG) monochromator.…”

Section: Methodsmentioning

confidence: 99%

Bicellar Mixtures Containing Pluronic F68: Morphology and Lateral Diffusion from Combined SANS and PFG NMR Studies

Soong

Nieh²,

Nicholson

et al. 2009

Langmuir

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Small angle neutron scattering (SANS) and pulsed field gradient (PFG) nuclear magnetic resonance (NMR) diffusion measurements were applied to examine morphology and diffusion in dimyristoyl- plus dihexanoyl-phosphatidylcholine bicellar mixtures, either neutral or negatively charged, incorporating a Pluronic triblock copolymer (F68). Negatively charged bicellar mixtures, doped with dimyristoylphosphatidylglycerol (DMPG), exhibited SANS profiles consistent with a perforated lamellar morphology for the magnetically alignable phase. Correspondingly, F68 diffusion in this magnetically aligned phase was normal Gaussian, in that the mean square displacements increased linearly with the experimental diffusion time, with a lateral diffusion coefficient of 1.9 x 10(-11) m(2) s(-1) consistent with a lipid bilayer inserted configuration. Neutral bicellar mixtures, that is, lacking DMPG, in contrast, displayed SANS profiles characteristic of ribbons arranged in such a fashion as to produce extended lamellae. Within the lamellae, the ribbons exhibited an in-plane periodicity (interribbon) of between 120 and 140 A. Correspondingly, F68 diffusion was non-Gaussian, exhibiting a square root diffusion time dependence of the mean square displacement indicative of one-dimensional curvilinear diffusion. The presence or absence of DMPG, rather than of F68, dictated the ribbon versus lamellar morphology, with F68 reflecting this difference via its lateral diffusion behavior. Although ribbons have been reported previously, this is the first study to show that they aggregate, most likely into extended lamellar sheets, and eventually fold into multilamellar vesicles.

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Adapting a triple-axis spectrometer for small angle neutron scattering measurements

Cited by 7 publications

References 15 publications

Adapting a triple-axis spectrometer for small angle neutron scattering measurements

Adapting a triple-axis spectrometer for small angle neutron scattering measurements

Morphological Characterization of DMPC/CHAPSO Bicellar Mixtures: A Combined SANS and NMR Study

Bicellar Mixtures Containing Pluronic F68: Morphology and Lateral Diffusion from Combined SANS and PFG NMR Studies

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