| Abstract
| - The nanoscale structures of multilayer metal−phosphonate thin films prepared via a layer-by-layer assemblyprocess using Zr4+ and 1,12-dodecanediylbis(phosphonic acid) (DDBPA) or porphyrin square bis(phosphonicacid) (PSBPA) were studied using specular X-ray reflectivity (XRR), X-ray fluorescence, and long-periodX-ray standing wave (XSW) analysis. The films were prepared in 1, 2, 3, 4, 6, and 8 layer series on bothSi(001) substrates for XRR and on 18.6 nm period Si/Mo layered-synthetic microstructure X-ray mirrors forXSW. After functionalizing the SiO2 substrate surfaces with a monolayer film terminated with phosphonategroups, the organic multilayer films were assembled by alternating immersions in (a) aqueous solutionscontaining Zr4+or Hf4+ (final metal layer only) cations and then (b) organic solvent solutions of PO3−R−PO34-, where R was DDBPA or PSBPA spacer molecule. The Hf4+ cation served as the marker for the topsurface of the films, whereas the Zr4+ cation was present in all other layers. The PSBPA also contained Znand Re atoms at its midline which served as heavy-atom markers for each layer. The long-period XSWgenerated by the 0th- (total external reflection) through 4th-order Bragg diffraction conditions made it possibleto examine the Fourier transforms of the fluorescent atom distributions over a much larger qz range in reciprocalspace which permitted simultaneous analysis of Hf, Zn/Re, and Zr atomic distributions.
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