Structural study of Langmuir–Blodgett films by scanning surface potential microscopy

Abstract

In this paper we describe the structural study of Langmuir–Blodgett (LB) films with a scanning surface potential microscope (SSPM) together with an ordinary atomic force microscope (AFM). The SSPM is a new type of high-resolution potentiometry due to electrostatic force microscopy and is a member of the AFM family. Our SSPM is a modified Kelvin probe force microscope, and is based upon the design of a recently developed scanning Maxwell stress microscope (SMM). This microscope can be used to study distribution of the surface potential or the contact potential difference (CPD) with submicrometer spatial resolution. We have applied this microscope to the study of molecular orientation of amphiphilic molecules in LB films. The surface dipole moments due to the terminal CH3 group of the long alkyl chain and the hydrophilic head group are used to study the orientation in the multilayered structures of LB films. In the present work, we focused on reorientation of the amphiphilic molecules in LB films during monolayer transfer and by oxidation of the substrate surface.