Nanoscale Chemical Analysis Beyond the Diffraction Limit: AFM-IR and s-SNOM (AFM-IR AND S-SNOM)

Atomic force microscopy-infrared spectroscopy (AFM-IR) is
an analytical technique that enables chemical
characterization of materials with nanometer scale spatial
resolution. In AFM-IR, IR laser light is focused onto the area
of the sample directly underneath the tip of an AFM. The
absorption of IR radiation by the sample causes local
thermal expansion which is detected by the AFM probe.
The equipment essentially measures IR spectra from
nanometer scale regions of the sample. It can also create
chemical composition maps that show the spatial
distribution of different chemical components present in an
unknown sample. The resolution can currently reach less
than 10 nm with sensitivity down to a monolayer. The
equipment can also be coupled with another technique
called scattering type scanning-near-field optical
microscopy (s-SNOM) which allows characterization of
complex optical properties of materials. AFM-IR and s-
SNOM enable fast, label-free, non-destructive and highly
sensitive chemical and optical imaging of a variety of
materials and nanostructures. The techniques are
applicable to a broad variety of materials including
graphene and related 2D materials, metal organic- and
covalent organic frameworks, perovskites, organic
semiconductors, biomaterials, and cellulose based
nanomaterials. This equipment is indispensable for the characterization of materials with heterogenity at the
nanoscale.