Narrow Results

Atomic force microscopy and X-ray reflectivity methods are used to characterize a surface morphology which includes the information of rms roughness, roughness exponent, and the height–height correlation length. Two major reasons to interpret the discrepancy of rms roughness data measured by AFM and X-ray reflectivity are (1) the bandpass of power spectra density is different and (2) the X-ray reflectivity probes the high density buried layer.

The influence of controlled humidity on the phase transformation of CTAB templated silica thin films is studied by time-resolved in situ GISAXS measurements. It is shown that during a short period of time the silica matrix is flexible enough to follow the morphologic changes of the cylindrical micelles into spherical ones. During this time water can be uptaken and outtaken from the film. The evolution of the lattice parameters upon cycling dry and humid air is presented and discussed.

Langmuir monolayer films of the tetracationic porphyrin tetrakis(octadecyl-4-pyridinium)porphyrinatozinc(II) bromide on various salt containing subphases were analyzed using surface pressure-area isotherms and X-ray reflectivity. The use of these complementary techniques showed that the porphyrin molecules undergo changes in conformation upon compression. Two main phases were identified, one in which the porphyrin moiety is parallel to the subphase and one in which the porphyrin moiety is tilted out of the plane. The addition of different salts into the subphase brought about changes in film behaviour, which are explained in terms of a lyotropic series.

The following sections are included:

• Introduction

• X-ray Reflectivity
  • Index on Refraction
  • Reflection from Interfaces
  • The Penetration Depth

• XAFS
  • Basic Principles of EXAFS
  • Detection of XAFS for Thin Films
    • Glancing Angle Techniques
    • Fluorescence Detection
    • Electron Yield Detection

• Experimental Examples
  • Transition Metal/Aluminum Bilayers
  • Total Reflection X-ray Flourescence Spectroscopy
  • Reflectivity Study on Liquid-vapor Interfaces
  • Polarization Dependent XAFS Studies on Thin Hetero-epitaxial Metallic Films
  • In situ MOCVD Growth Studies

• Acknowledgments

• References