Growth of atomically smooth films of metal-arachidates by Langmuir-Blodgett technique

Abstract

In this paper, we report synthesis of atomically smooth Ni-arachidate films using Langmuir-Blodgett technique. The interaction between arachidic acid monolayer and nickel ion has been investigated as a function of subphase pH by measuring the compression isotherms at the air/water interface. As the pH is increased, the compressible liquid (L₂) phase is observed over a smaller range of surface pressure (π) and area/mol (A) until at high enough pH the L₂ phase is altogether absent. A further increase in pH does not result in any additional change in the isotherm. This is a general trend observed for all bivalent cations but the disappearance of L₂ phase occurs at different pH values for different ions. The atomically smooth monolayers are deposited when the pressure is beyond the L₂ phase (typically ∼35 mN/m). Along with the isotherms, monolayer of nickel arachidate deposited on mica, were studied thoroughly using Atomic force Microscopy. Atomic force microscope images show atomically smooth and defect free surface of nickel arachidate transferred on mica substrate. The images allow proper determination of the lattice vectors.