Surface Study of Langmuir-Blodgett Films by Electron Microscopy and X-Ray Reflectivity

Allain, M.; Benattar, J. J.; Rieutord, F.; Robin, Philippe

doi:10.1209/0295-5075/3/3/010

Cited by 13 publications

(7 citation statements)

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“…This cannot be explained by regular damping with increasing incidence, since there is about one order in magnitude between the intensities. The [22,23] and with our observations made by electron microscopy on replicas [24]. Micrographs taken on these samples look rather blurred, on account of the disorder of the last layer.…”

supporting

confidence: 62%

X-Ray Optics in Langmuir-Blodgett Films

Benattar¹,

Bosio

Rieutord³

1988

Physics, Fabrication, and Applications of Multilayered Structures

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Résumé. 2014 Abstract. 2014 Stratified media and especially Langmuir-Blodgett films give rise to interesting features of the Xray reflectivity curves at grazing incidences. We have studied the projection of the electronic density along the normal to the layers of differently sequenced L.B. Films of behenic acid, in order to correlate their structure with the particular interference patterns occurring around (00l) Bragg peaks. Using both optical formalism and kinematical theory for X-rays, we have analysed these various interference phenomena. Moreover, we found a new untilted structure of these systems.

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supporting

confidence: 62%

X-Ray Optics in Langmuir-Blodgett Films

Benattar¹,

Bosio

Rieutord³

1988

Physics, Fabrication, and Applications of Multilayered Structures

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“…In x-ray diffraction from organic thin films the refractive index n can be approximated by nϭ1Ϫ␦ with ͑absorption can be neglected 8 …”

Section: A Fresnel Reflectivity From Smooth and Rough Interfacesmentioning

confidence: 99%

Numerical analysis of x-ray reflectivity data from organic thin films at interfaces

Asmussen

Riegler

1996

The Journal of Chemical Physics

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Articles you may be interested inXray reflectivity study of behenic acid Langmuir-Blodgett mono and multilayers on SiO2 surfaces asdeposited and after thermal treatment: Influence of substrate/film interactions on molecular ordering and film topology Static and dynamic structural analysis of a saturated solution of ZnBr2 in water: Anomalous xray diffraction and molecular dynamics simulations Near edge xray absorption fine structure investigation of the orientation and thermally induced order-disorder transition in thin organic films containing long chain hydrocarbons Higher order structure analysis of nanomaterials by spectral reflectance of laserplasma soft xray AIP Conf.An efficient numerical analysis procedure of x-ray reflectivity data from ultrathin organic films at interfaces is presented. It allows virtually exact modeling of reflectivity data in the entire q-vector range including the critical angle and below with minimum fit parameters and calculation effort. The electron density profile is interpreted as a linear superposition of the air/film interface, the internal film structure, and the film/substrate interface. The reflectivities at the interfaces are calculated from the accurate Fresnel reflectivities. The internal film structure is parameterized in a Fourier series and its reflectivity contribution is calculated from refraction-corrected, approximated ͑linearized͒ Fresnel reflectivities. Additionally, a new way of weighing measurement errors is introduced. It allows the selective optimization of the fit in those data sections which are considered especially significant. Finally, we show further how to determine the degree of correlation ͑interdependencies͒ between the fit parameters and how to obtain absolute errors ͑the significance͒ of all fit parameters.

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“…The bulk structures of Langmuir−Blodgett (LB) thin films have been extensively investigated by several methods including X-ray scattering, neutron scattering, and vibration spectroscopy due to their potential applications in the field of functional materials and biomembranes. − Recently, it has been shown that the surface structures of the LB films are different from those normally expected for the bulk structure of multilayer LB films. , The scattering measurements demonstrated that the top layer of the LB film of the fatty acid is rather disordered compared with their inner layers. − On the other hand, several atomic force microscopy (AFM) observations showed that wide long-range ordered domains with some irregularly distributed holes to a depth of one or two bilayers exist on the surface of the LB films. − Schwartz et al investigated the morphologies of the LB films of a fatty acid on Si or mica surfaces by AFM during its submerging process in a buffered aqueous subphase and found that the reorganization of the LB films takes place from the bilayer step defects. ,, They attributed the driving force for the reorganization to be the formation of headgroup−headgroup interfaces, which are stabilized by the strong electrostatic interaction with divalent metal cations at the expense of the headgroup−substrate and headgroup−water interfaces. ,, The reorganization phenomenon has also been observed for other LB films. ,, On the other hand, it is well-known that the divalent metal cation plays an important role in forming stable multilayer LB films of fatty acid but its role in the surface structure of the LB film is still not very clear. Not only the morphology of the LB films but also the quantitative characterization of the surface molecular structures of LB films by vibration spectroscopy is strongly expected to provide a better understanding of the surface reorganization process.…”

Section: Introductionmentioning

confidence: 99%

Cd²⁺-Induced Interfacial Structural Changes of Langmuir−Blodgett Films of Stearic Acid on Solid Substrates: A Sum Frequency Generation Study

et al. 2003

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The molecular structures and their stabilities at the outmost-layer of the Langmuir-Blodgett (LB) films of stearic acid on solid substrates have been investigated by a highly surface-sensitive spectroscopic technique, sum frequency generation (SFG), in air and in aqueous solution, using the combination of both normal and deuterated stearic acid. Peaks observed in the SFG spectra are mainly attributed to the terminal methyl group at the outmost layer of the LB films. The SFG spectra in air are virtually identical and are independent of the odd-even property and thickness (1-12) of the LB films, indicating that the even-numbered LB film changes its surface structure after passing through the interface between the water subphase and air, especially when the Cd2+ cation was included in the water subphase. Furthermore, we have demonstrated for the first time using in situ SFG measurement that the interfacial molecular structure at the LB bilayer of stearic acid on the hydrophilic substrates significantly change with immersion in the water subphase containing Cd2+ cation while such a structural change has not been observed in the water subphase without Cd2+. These results clearly indicate that a reorganization process takes place on the surface of the stearic acid bilayer induced by the Cd2+ cation. The electrostatic interaction between the carboxylate headgroup of stearic acid via the Cd2+ cation seems to play an important role in the surface reorganization process both in air and in solution.

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Surface Study of Langmuir-Blodgett Films by Electron Microscopy and X-Ray Reflectivity

Abstract: Using the combination of electron microscopy and X-ray reflectivity, we have * * *We wish to thank M. DUPEYRAT, C. WILLIAMS and M. KLEMAN for helpful discussions.

Cited by 13 publications

References 13 publications

X-Ray Optics in Langmuir-Blodgett Films

X-Ray Optics in Langmuir-Blodgett Films

Numerical analysis of x-ray reflectivity data from organic thin films at interfaces

Cd²⁺-Induced Interfacial Structural Changes of Langmuir−Blodgett Films of Stearic Acid on Solid Substrates: A Sum Frequency Generation Study

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Surface Study of Langmuir-Blodgett Films by Electron Microscopy and X-Ray Reflectivity

Abstract: Using the combination of electron microscopy and X-ray reflectivity, we have * * *We wish to thank M. DUPEYRAT, C. WILLIAMS and M. KLEMAN for helpful discussions.

Cited by 13 publications

References 13 publications

X-Ray Optics in Langmuir-Blodgett Films

X-Ray Optics in Langmuir-Blodgett Films

Numerical analysis of x-ray reflectivity data from organic thin films at interfaces

Cd2+-Induced Interfacial Structural Changes of Langmuir−Blodgett Films of Stearic Acid on Solid Substrates: A Sum Frequency Generation Study

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Cd²⁺-Induced Interfacial Structural Changes of Langmuir−Blodgett Films of Stearic Acid on Solid Substrates: A Sum Frequency Generation Study