Principles and applications of grazing incidence X-ray and neutron scattering from ordered molecular monolayers at the air-water interface

Als‐Nielsen, J.; Jacquemain, D.; Kjær, Kristian; Leveiller, F.; Lahav, Meir; Leiserowitz, Leslie

doi:10.1016/0370-1573(94)90046-9

Cited by 689 publications

(691 citation statements)

References 131 publications

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“…The scattering of X-rays is elastic, and therefore the wave vectors k i and k f of the incident and diffracted photons have the same absolute value. The horizontal (in-plane) component of the scattering vector Q ) k i -k f is given by and the vertical (out-of-plane) component by the following equation: 24,25 Fabrication of Line Microband Electrodes. Electrochemical measurements at the air/water interface required specially designed "line" microelectrodes that can be positioned in the plane of the air/water interface.…”

Section: Methodsmentioning

confidence: 99%

“…The structures of these aggregates and the fully compressed films were determined using grazing incidence X-ray diffraction (GIXD). 24,25 Subsequent electrochemical characterization of the electron transport kinetics involved "line" microelectrodes designed to function in the plane of the air/water interface where they can address electrochemically redox species forming monolayer films. [26][27][28] Combination of these techniques allowed us to show that diffusive electron transport involves electron hopping between neighboring osmium sites with a unimolecular rate constant of k 1 ) 4.7 × 10 8 s -1 .…”

Section: Introductionmentioning

confidence: 99%

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Structure and Lateral Electron Hopping in Osmium-tris-4,7-diphenylphenanthroline Perchlorate Monolayers at the Air/Water Interface

et al. 1999

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Osmium tris-diphenylphenanthroline perchlorate (Os(DPP) 3 ) can be spread at the air/water interface where it forms solid monolayer films. Brewster angle microscopy revealed that these films consist of irregular ca. 100 to 1000 µm diameter 2D aggregates which coalesce upon compression to form continuous films. Grazing incidence X-ray diffraction data showed that the structure of the aggregates is independent of the degree of monolayer compression and features a 2D lattice of hexagonally close-packed Os(DPP) 3 centers with Os-Os distances of 12.57 Å. The latter is 4 to 24% shorter than the Ru-Ru distances found in the 3D monoclinic crystal of an isostructural Ru (DPP) 3 . Two dimensional electrochemical measurements carried out with line microelectrodes at the air/water interface were used to study kinetics of the lateral electron transport in these Langmuir monolayers. Electron transport involves electron hopping on the 2D lattice of the osmium sites where the individual electron transfer steps between Os II (DPP) 3 and Os III (DPP) 3 take place with the rate constant k 1 ) 4.7 × 10 8 s -1 . Percolation theory was used to account for the observed increase of the electron hopping rates during monolayer compression on the water surface resulting in an increase of the extent of connectivity and thus electroactivity of the initially formed 2D Os(DPP) 3 aggregates. Percolation theory also accounts well for the dependence of the electron hopping rates on the composition of fully compressed Os-(DPP) 3 /Ru(DPP) 3 monolayers in which the ruthenium species were used to homogeneously dilute the Os-(DPP) 3 sites. In contrast, in Os(DPP) 3 /octadecanol monolayers, macroscopic self-segregation of the two components was inferred from a larger positive shift of the apparent percolation threshold in the lateral electron hopping.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structure and Lateral Electron Hopping in Osmium-tris-4,7-diphenylphenanthroline Perchlorate Monolayers at the Air/Water Interface

et al. 1999

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“…1-3 A principal challenge in this general area of physics has been to identify real, well defined physical systems that are suitable for experimental studies. Examples of two-or quasi-twodimensional systems that have been investigated for this purpose in recent years include rare gases adsorbed on solid substrates, [3][4][5][6] freely suspended thin liquid crystal films, [7][8][9][10] and Langmuir monolayers 11,12 of simple long-chain molecules such as fatty acids, [13][14][15][16][17][18][19][20][21][22][23] alcohols, [24][25][26][27] esters, 28 etc. Related statistical phenomena at surfaces and interfaces that have been often studied for more practical motivations, include wetting, [29][30][31] premelting and reconstruction of crystalline surfaces, [32][33][34][35] and surface induced order at liquid surfaces.…”

Section: Introductionmentioning

confidence: 99%

C 60 -propylamine adduct monolayers at the gas/water interface: A Brewster angle microscopy and x-ray scattering study

Fukuto

Penanen

Heilmann

et al. 1997

The Journal of Chemical Physics

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Brewster angle microscopy ͑BAM͒, x-ray specular reflectivity and grazing-incidence x-ray diffraction ͑GID͒ studies of C 60 -propylamine adduct monolayers at the gas/water interface as a function of molecular area are reported. At large molecular areas (AϾϳ150 Å 2 /molecule), BAM images reveal macroscopic heterogeneity in the film, consisting of the coexistence between regions covered with uniform solidlike monolayer and bare water surface. After compression to a limiting molecular area of 150 Å 2 /molecule, the film is observed to be homogeneous, with the uniform monolayer covering the entire available surface. Both the x-ray reflectivity results and the GID patterns are consistent with the formation of a uniform monolayer at Aϳ150 Å 2 /molecule, while the little dependence that the GID patterns have on the molecular area for AϾϳ150 Å 2 /molecule is consistent with the heterogeneity in the film. Upon further compression to higher densities (AϽϳ120 Å 2 /molecule), the x-ray reflectivity results suggest the formation of a partial layer either at the molecule/gas interface or at the molecule/water interface. In this high density regime, the shift in the observed GID pattern with molecular area is much smaller than would be expected if the film were to remain a homogeneous monolayer, also consistent with the formation of an inhomogeneous partial layer. The analysis of the broad GID pattern observed from a uniform monolayer in terms of a model 2D radial distribution function, implies a short range positional correlation, extending to only a few molecular distances. The average nearest neighbor distance (dϳ13 Å͒, extracted from the GID analysis, is consistent with the limiting molecular area (Aϳ150 Å 2 /molecule) assuming local hexagonal packing. These results together with the sharp facets observed in the BAM images demonstrate that the monolayer when uniform is a two-dimensional amorphous solid.

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“…Synchrotron grazing incidence X-ray diffraction (GIXD) data collection was performed with a liquid surface diffractometer at the undulator beamline BW1 which was located in the synchrotron radiation research laboratory HASYLAB at DESY (Hamburg, Germany) [9,10]. GIXD measurements were performed using a Langmuir trough with an area of 480 cm 2 placed in an air-tight aluminum container with Kapton windows.…”

Section: Synchrotron Grazing Incidence X-ray Diffractionmentioning

confidence: 99%

“…The incident grazing angle αi of the X-ray beam was ~0.85 αc, where αc = 0.129º is the critical angle for total external reflection from an air/water interface. This limits the penetration depth of the beam to ~8 nm [9]. Thus, X-ray scattering from the water subphase contributing to the background intensity is efficiently reduced allowing accurate measurements of the X-ray photons diffracted from the monolayer.…”

Section: Synchrotron Grazing Incidence X-ray Diffractionmentioning

confidence: 99%

Structural Characterization of Self-Organized Mono- and Multilayers of Partly Fluorinated Polydialkoxyphosphazenes at the Air/Water Interface

et al. 2017

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Abstract.We report studies of the collapse of monolayers of mesomorphic poly [bis-(2,2,3,3,4,4,5,5-octafluoropentoxy)phosphazene] and poly [bis-(2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptoxy)phosphazene]. The structure of the films has been examined at different stages of the collapse process by synchrotron grazing incidence X-ray diffraction. Surface pressure-surface area isotherms show that these films undergo a stepwise collapse with formation of multilayers. Grazing incidence X-ray diffraction reveals only one diffraction peak for the monolayer as well as for multilayers of the two polymers studied, which corresponds to an in-plane interchain spacing d = 15.2±0.1˚Å and 17.6±0.5˚Å, respectively. The in-plane correlation length ξxy reaches ca. 500 Å for PFP-C5 (33 macromolecules) and ca. 400 Å for PFP-C7 (23 macromolecules), implying a certain mesoscale order similar to a quasi-long-range one.

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Principles and applications of grazing incidence X-ray and neutron scattering from ordered molecular monolayers at the air-water interface

Cited by 689 publications

References 131 publications

Structure and Lateral Electron Hopping in Osmium-tris-4,7-diphenylphenanthroline Perchlorate Monolayers at the Air/Water Interface

Structure and Lateral Electron Hopping in Osmium-tris-4,7-diphenylphenanthroline Perchlorate Monolayers at the Air/Water Interface

C 60 -propylamine adduct monolayers at the gas/water interface: A Brewster angle microscopy and x-ray scattering study

Structural Characterization of Self-Organized Mono- and Multilayers of Partly Fluorinated Polydialkoxyphosphazenes at the Air/Water Interface

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