Relating structure with morphology: A comparative study of perfect Langmuir-Blodgett multilayers

Atomic force microscopy and X-ray reflectivity of metal-stearate (MSt) Langmuir-Blodgett films on hydrophilic Silicon (10 0), show dramatic reduction in 'pinhole' defects when metal M is changed from Cd to Co, along with excellent periodicity in multilayer, with hydrocarbon tails tilted 9.6 degrees from vertical for CoSt (untilted for CdSt). Near edge X-ray absorption fine structure (NEXAFS) and Fourier transform infra-red (FTIR) spectroscopies indicate bidentate bridging metal-carboxylate coordination in CoSt (unidentate in CdSt), underscoring role of headgroup structure in determining morphology. FTIR studies also show increased packing density in CoSt, consistent with increased coverage. (C) 2007 Elsevier B.V. All rights reserved.