Synchrotron FTIR Microscopy of Langmuir–Blodgett Monolayers and Polyelectrolyte Multilayers at the Solid–Solid Interface

Synchrotron FTIR microscopy has been used to probe the structure of model boundary lubricant layers confined at the solid-solid interface. The combination of high brightness of the IR source and a novel contact geometry that uses a hemispherical internal reflection element as the means for light delivery has enabled the detection of <2.5 nm thin monolayer lubricant layers in the solid-solid contact, in addition to allowing for spectral acquisition from specific regions of the contact. Spectra of hydration water from within a confined polyelectrolyte multilayer film have also been acquired, highlighting the altered hydrogen bonding environment within the polymer layer.