Phase determination and inversion in specular neutron reflectometry

Majkrzak, C. F.; Berk, N. F.; Dura, Joseph A.; Satija, Sushil K.; Karim, Alamgir; Pedulla, Joseph; Deslattes, R

doi:10.1016/s0921-4526(98)00260-9

Cited by 49 publications

(28 citation statements)

References 8 publications

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“…3 and 4 has proven, so far, to be experimentally practical. 9 In this Brief Report we show a simple extension of the method that substitutes variation of the uniform incident and/or transmitting media for variation of buried layers of finite thickness. Such an approach is suited to a substantial number of systems in which the film is in contact with an aqueous reservoir serving as the incident or transmitting medium, whose SLD can be readily varied by exchanging heavy for light water.…”

Section: Introductionmentioning

confidence: 99%

Exact determination of the phase in neutron reflectometry by variation of the surrounding media

Majkrzak¹,

Berk²

1998

Phys. Rev. B

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Recently, it has been shown that the complex amplitude for neutrons specularly reflected from a film can be determined exactly at all accessible wave-vector transfers, including those for which the Born approximation is invalid, through the use of buried reference layers of finite thickness. Given the phase of reflection, it is then possible to solve the one-dimensional inverse-scattering problem directly, without resort to potentially ambiguous fitting procedures, to obtain a unique scattering length density depth profile for a laminar thin-film structure. Here we describe an extension of that phase determination method which utilizes controlled variations of the scattering length density of the incident and/or substrate medium instead of reference layers of finite thickness. This technique is of practical importance for thin-film systems involving either gas-liquid or solidliquid interfaces in which the scattering length density of the liquid can be varied in a known way, as in an aqueous media consisting of a mixture of H 2 O and D 2 O.

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Section: Introductionmentioning

confidence: 99%

Exact determination of the phase in neutron reflectometry by variation of the surrounding media

Majkrzak¹,

Berk²

1998

Phys. Rev. B

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“…The scattering length density of a magnetic layer, such as permalloy in a magnetic field, is different for the spin up/down states; opening up the possibility of obtaining two magnetic contrast measurements simultaneously. This technique was conceived at NIST, as providing a reference that would enable the phase problem, inherent in a reflectivity measurement, to be circumvented by facilitating a direct inversion of the data (Majkrzak et al 1998). Although Hughes et al still transform the reflectivity to a structure by means of a fitting procedure, rather than direct inversion, it is clear that the simultaneous measurement of the two magnetic contrasts serves as a strong constraint on the fitting procedure, increasing the robustness of the extraction of structural details.…”

Section: Floating Bilayersmentioning

confidence: 99%

Neutron Reflectivity as a Tool for Physics-Based Studies of Model Bacterial Membranes

Barker

McKinley

Titmuss

2016

Biophysics of Infection

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The principles of neutron reflectivity and its application as a tool to provide structural information at the (sub-) molecular unit length scale from models for bacterial membranes are described. The model membranes can take the form of a monolayer for a single leaflet spread at the air/water interface, or bilayers of increasing complexity at the solid/liquid interface. Solid-supported bilayers constrain the bilayer to 2D but can be used to characterize interactions with antimicrobial peptides and benchmark high throughput lab-based techniques. Floating bilayers allow for membrane fluctuations, making the phase behaviour more representative of native membranes. Bilayers of varying levels of compositional accuracy can now be constructed, facilitating studies with aims that range from characterizing the fundamental physical interactions, through to the characterization of accurate mimetics for the inner and outer membranes of Gram-negative bacteria. Studies of the interactions of antimicrobial peptides with monolayer and bilayer models for the inner and outer membranes have revealed information about the molecular control of the outer membrane permeability, and the mode of interaction of antimicrobials with both inner and outer membranes.

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“…[10] and discretize the Marchenko equation (7). In particular we introduce a mesh in the coordinate x ðx i ; i ¼ 1; .…”

Section: Inverse Scattering and Information Entropymentioning

confidence: 99%

“…To our knowledge only the method of Ref. [6] has been implemented experimentally for a specific case [7]. Because of the missing phase information additional assumptions are required to uniquely reconstruct the depth profile from experimental reflection data.…”

Section: Introductionmentioning

confidence: 99%

Profile reconstruction from neutron reflectivity data and a priori knowledge

Leeb

2008

Nuclear Instruments and Methods in Physics Research Section A:

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Phase determination and inversion in specular neutron reflectometry

Cited by 49 publications

References 8 publications

Exact determination of the phase in neutron reflectometry by variation of the surrounding media

Exact determination of the phase in neutron reflectometry by variation of the surrounding media

Neutron Reflectivity as a Tool for Physics-Based Studies of Model Bacterial Membranes

Profile reconstruction from neutron reflectivity data and a priori knowledge

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