Xiaoji Xu Research Group on Scanning Probe Microscopy and Infrared Nanospectroscopy 

Where instrument development unravels nature's secrets at the nanoscale

Microscopy opens many possibilities for understanding the composition, organization, and interaction of inhomogeneous materials. In our group, we develop variants of scanning probe microscopy (SPM) to study macromolecules, heterogeneous materials, and nanostructures to decipher their chemical, electrical, and mechanical properties. 

Schematic summary of research areas

 One challenge of optical microscopy is Abbe's diffraction limit to about half of the wavelength (λ/2). Materials and structures often have nanometer-scale features much smaller than the diffraction limit—not directly resolvable by traditional optical microscopy. We work on atomic force microscopy (AFM)--based infrared (IR) and optical spectroscopy to bypass the diffraction limit, sometimes combined with ultrafast lasers or plasma emissions. We also work on new types of multimodal AFM-based electrical imaging methods, and fun & useful things with AFM and infrared lasers.

A SPM-based photothermal infrared microscopy with multimodal chemical/mechanical/electrical imaging capabilities

Ambient condition surface potential measurement with 10 nm spatial resolution

The PFIR microscopy has been applied across a wide range of samples for label-free chemical nano-imaging and spectroscopy

We integrate AFM photothermal detection with femtosecond IR pulse sequence excitation to achieve action-based 2DIR spectroscopy without the restriction from Abbe's diffraction limit. 

A new type of scattering near-field microscopy with direct three-dimensional response collections

We are actively seeking collaboration opportunities to unravel nature's secrets at the nanoscale, together.

Contact: xgx214@lehigh.edu 

Our mailing address:

Department of Chemistry, Lehigh University

6 E Packer Ave.

Bethlehem, PA, 18015, United States

Our lab is located in the Sinclair Optical Laboratory of Lehigh University, in Bethlehem, Pennsylvania, US