Characterization of Langmuir-Blodgett Films by Electron Spin Resonance Spectroscopy

Abstract

Langmuir-Blodgett (LB) films built up with amphiphilic molecules have well-known optical, electrical and magnetic properties. For most applications, it is fundamentally important to understand the structure of the films. Electron spin resonance (ESR) spectroscopy has proven to be a powerful tool for measuring sample structure, yet few studies have been performed on monolayer LB films, primarily due to a lack of sufficient sensitivity. In this work, the fabrication and structural characterization of novel spin-labeled LB films is discussed and demonstrated. Mixed 16-DSA/SA monolayer films containing 10^13 - 10^14 free-radical electron spins were created and characterized for the first-time using continuous wave (CW) ESR spectroscopy and atomic force microscopy (AFM). Through simulation and image analysis, an order parameter was extracted suggesting that the sample assumes a multi-domain liquid crystal structure when deposited on a solid substrate.