Optical studies on composite Langmuir-Blodgett films containing ytterbium bis-phthalocyanine

Author： Ray A. K. Nabok A. V. Hassan A. K. Silver J. Marsh P. Richardson T.

ISSN： 1463-6417

Source： Philosophical Magazine B, Vol.79, Iss.7, 1999-07, pp. : 1005-1019

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Abstract

Langmuir films of pure ytterbium bis-phthalocyanine (YbPc2) molecules and its mixtures with calix[4]resorcinarene (C[4]RA) molecules were studied by UVvis absorption spectra and surface pressure-area (Pi - A) isotherm measurements. Langmuir-Blodgett (LB) films of both pure YbPc2 and YbPc2-C[4]RA mixtures were produced and characterized with UV-vis spectra and surface plasmon resonance (SPR). In the case of LB films of pure YbPc2 molecules, values of 1.68 107 m-1 and 1.76% were found for the absorption coefficient at spectral maxima and the reflectance loss. Mixed YbPc2-C[4]RA films give smaller values depending on the mixing ratio. SPR measurements, made in two media with different refractive indices, yielded accurate values of thickness of 2.06 0.06 nm and refractive index of 1.70 0.02 for LB films of pure YbPc2 molecules. Electrochromic effects, driven by electrochemical oxidation/reduction of the Yb central atom, were registered in LB films of pure YbPc2 molecules by both UV-vis absorption spectra and SPR measurements.