Nanoscale Analytics on Organic Materials using nano-FTIR

Scattering-type scanning near-field optical microscopy (s-SNOM) has become a key technology to study the chemical composition of organic materials at the nanoscale. This AFM-based technology exploits the strong confinement of light at the end of a sharp, metallic AFM tip to generate a nanoscale optical hotspot at the sample surface. Importantly, the amplitude and phase of the light within the optical hotspot correlates with the absorption and reflectivity properties of the sample directly below the tip.

With the development of Fourier transform infrared spectroscopy on the nanoscale (nano-FTIR) and hyperspectral nano-spectroscopy, we have successfully extended s-SNOM towards a complete spectroscopic analysis tool that is capable of analyzing complex polymer nanostructures with <10 nanometer precision. With tremendous nanoscale sensitivity, the nano-FTIR spectroscopy enables not only nano-chemical identification and to explore local distribution of polymer blends but it also offers information about local orientation of polymer chains in crystalline organic semiconductors and in polymer monolayers. Various examples of s-SNOM measurements on different polymer and biomaterial samples will be presented.

Fig. 1: Imaging of a 10 nm thin PEO monolayer at 1123 cm-1 (asy. C-O-C stretching) shows self-assembled nano-structures and areas of different material thickness. High contrast absorption images allow to clearly distinguish between mono- and bilayer film areas.