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Seeing is believing: revealing nanoscale secrets through spectroscopic imaging  

                                       

figure_1_website          Domains of a block copolymer revealed with 10 nm spatial resolution by PFIR microscopy.

Microscopy opens many possibilities for understanding the composition, organization, and interaction of inhomogeneous materials. In our group, we develop spectroscopic microscopy below the optical diffraction limit to study macromolecules, heterogeneous materials, and nanostructures in order to decipher their chemical, electric, and mechanical properties.

One challenge of optical microscopy is the diffraction limit of light, which is approximately a half of the wavelength. Nano-materials often have features smaller than the diffraction limit that is not resolvable by traditional optical microscopy. To overcome this challenge, we work on two types of super-resolution infrared microscopies that combines atomic force microscopy with laser radiations:

1.  Peak force infrared (PFIR) microscopy and multipulse PFIR microscopy in both air phase and liquid phase.

2. Scattering-type scanning near-field optical microscopy (s-SNOM)  More specifically, Peak force scattering-type near-field optical microscopy (PF-SNOM) that can collect 3D near-field response cube.

We are also interested in developing and refining other modalities of atomic force microscopy through instrumentation. For example, we have developed the Pulsed force Kelvin probe force microscopy (PF-KPFM).

We are interested in studying materials that may be nanoscale heterogeneous, such as block copolymers, polymer blends,  protein aggregates, polaritonic nanostructures, oil shale, urban aerosols, and photovoltaics.