Influence of colloidal subphase pH on the deposition of multilayer Langmuir–Blodgett films of gold clusters

Abstract

Negatively charged carboxylic acid derivatized gold colloidal particles have been immobilized at the air/water interface using positively charged fatty amine Langmuir monolayers. The degree of cluster incorporation into the Langmuir monolayer has been systematically controlled by varying the charge on the surface amine through the colloidal subphase pH. This affects the quality of multilayer gold cluster films transferred to different substrates by the Langmuir–Blodgett method. Pressure–area isotherms were measured to follow cluster adsorption at the air/water interface while characterization of the multilayer films was undertaken using quartz crystal microgravimetry, UV–VIS spectroscopy, contact angle measurements, transmission electron microscopy, ellipsometry and X-ray photoelectron spectroscopy. Incorporation of clusters into organic matrices in the manner outlined is promising for the synthesis of superlattice structures, mixed cluster systems, etc., which cannot be realized by current experimental methods.