x-ray Surface Scattering Studies of Molecular Ordering at Liquid-Liquid Interfaces

1999 ◽  
Vol 590 ◽  
Author(s):  
Mark L. Schlossman ◽  
Ming Li ◽  
Dragoslav M. Mitrinovic ◽  
Aleksey M. Tikhonov
Keyword(s):  
Chain Length ◽  
Capillary Wave ◽  
Potassium Phosphate ◽  
Wave Theory ◽  
Electron Density Profile ◽  
Surface Scattering ◽  
Biological Macromolecules ◽  
Liquid Interfaces ◽  
X Ray ◽  
Molecular Ordering

ABSTRACTWe present our recent progress in using synchrotron x-ray surface scattering techniques to study several different aspects of ordering at liquid-liquid interfaces. (1) We present measurements of the interfacial width at the water-alkane interface for a series of different chain length alkanes. The width for the shortest chain length studied is in agreement with capillary wave theory. However, significant deviations occur for longer chain lengths, indicating the presence of molecular ordering at the interface. (2) Under appropriate conditions, a surfactant monolayer forms at the interface between water and a hexane solution of a fluorinated surfactant. Reflectivity measurements that probe the electron density profile normal to the interface provide information about the surfactant ordering. This monolayer undergoes a solid to gas transition as a function of temperature. Diffuse scattering near the transition reveals the presence of islands. (3) Equilibrium interfaces between two aqueous phases containing PEG (polyethylene glycol) and potassium phosphate salts can be studied. We present studies of coherent capillary wave fluctuations between two interfaces of a thin film of this biphase system. We also demonstrate that biological macromolecules can be trapped and studied at this aqueous-aqueous interface.

scholarly journals X-Ray Studies of the Liquid/Vapor Interface: Water and Polymer and Fatty Acid Monolayers on Water

1989 ◽  
Vol 177 ◽  
Author(s):  
M. L. Schlossman ◽  
D. K. Schwartz ◽  
E. H. Kawamoto ◽  
G. J. Kellogg ◽  
P. S. Pershan ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Electron Density ◽  
Surface Pressure ◽  
Capillary Wave ◽  
Pure Water ◽  
Wave Theory ◽  
Lignoceric Acid ◽  
Vapor Interface ◽  
X Ray ◽  
Surface Normal

ABSTRACTX-ray specular reflectivity is used to study the liquid-vapor interface of pure water and of fatty acid and polymer monolayers at that interface. For the pure water surface the reflectivity was measured for three different spectrometer resolutions and simultaneous fits with only one free parameter to all of the data are in excellent agreement with the prediction of capillary wave theory for the RMS surface roughness. Diffuse scattering away from the specular condition, at wavevectors corresponding to those of the capillary waves, yields intensities and line shapes in agreement with theory with no significant adjustable parameters. Reflectivity from separate monolayers of co-poly 1,2-butadiene/butyl alcohol (50% random substitution) and lignoceric acid (CH3(CH2)22COOH) at the water/vapor interface are interpreted to obtain profiles of the average electron density ρ(z) as a function of distance z along the surface normal. For the polymer monolayer we find the following: 1) a local maximum in the electron density approximately 10% larger than that of the bulk polymer and 2) the RMS roughness of the vapor/polymer interface agrees with capillary wave theory predictions for the lower surface pressures. For the highest surface pressure the RMS roughness exceeds the value predicted by the capillary wave model. Measurements of reflectivity from a lignoceric acid monolayer, as a function of surface pressure throughout an isotherm (near room temperature), reveal the following behavior: 1) the overall thickness of the monolayer increases with increasing pressure and 2) the head groups occupy a progressively larger region along the surface normal as the pressure increases, indicating that they rearrange normal to the interface.

X-ray and neutron surface scattering for studying lipid/polymer assemblies at the air–liquid and solid–liquid interfaces

2000 ◽  
Vol 74 (3) ◽  
pp. 207-231 ◽  
Author(s):  
Jaroslaw Majewski ◽  
Tonya L. Kuhl ◽  
Joyce Y. Wong ◽  
Gregory S. Smith
Keyword(s):  
Surface Scattering ◽  
Liquid Interfaces ◽  
X Ray ◽  
Solid Liquid

Three-dimensional crystallization of membrane proteins

1988 ◽  
Vol 21 (4) ◽  
pp. 429-477 ◽  
Author(s):  
W. Kühlbrandt
Keyword(s):  
High Resolution ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Protein Complexes ◽  
Three Dimensional ◽  
Biological Macromolecules ◽  
X Ray ◽  
X Ray Crystallography ◽  
Membrane Protein Complexes ◽  
Essential Prerequisite

As recently as 10 years ago, the prospect of solving the structure of any membrane protein by X-ray crystallography seemed remote. Since then, the threedimensional (3-D) structures of two membrane protein complexes, the bacterial photosynthetic reaction centres of Rhodopseudomonas viridis (Deisenhofer et al. 1984, 1985) and of Rhodobacter sphaeroides (Allen et al. 1986, 1987 a, 6; Chang et al. 1986) have been determined at high resolution. This astonishing progress would not have been possible without the pioneering work of Michel and Garavito who first succeeded in growing 3-D crystals of the membrane proteins bacteriorhodopsin (Michel & Oesterhelt, 1980) and matrix porin (Garavito & Rosenbusch, 1980). X-ray crystallography is still the only routine method for determining the 3-D structures of biological macromolecules at high resolution and well-ordered 3-D crystals of sufficient size are the essential prerequisite.

X-ray reflectivity study of the influence of temperature fluctuations on the density profile of thin liquid films

2004 ◽  
Vol 219 (4) ◽  
Author(s):  
Robert Fendt ◽  
Michael Sprung ◽  
Christian Gutt ◽  
Oliver Hermann Seeck ◽  
Metin Tolan
Keyword(s):  
Density Profile ◽  
Temperature Fluctuations ◽  
Liquid Films ◽  
Electron Density Profile ◽  
Thin Liquid Films ◽  
Inversion Method ◽  
Layered System ◽  
Small Temperature ◽  
Influence Of Temperature ◽  
X Ray

AbstractWe report on X-ray reflectivity experiments of thin liquid heptane films. The films were examined using X-ray reflectivity and modelled both as a layered system using the Parratt algorithm and using a ´phase guessing´ inversion method. Our results combined with simulations of films of shrinking thickness show that small temperature instabilities during the investigation can cause artifacts in the electron density profile. These can easily be mistaken for density os cillations near the interface as might be expected for liquid molecules near a hard wall.

Laser-induced capillary wave at air/liquid interfaces in time domain

1999 ◽  
Vol 74 (10) ◽  
pp. 1495-1497 ◽  
Author(s):  
Kaori Yasumoto ◽  
Noboru Hirota ◽  
Masahide Terazima
Keyword(s):  
Time Domain ◽  
Capillary Wave ◽  
Liquid Interfaces
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