Xiaoji Xu Research Group on Scanning Probe Microscopy and Nanospectroscopy at Lehigh University

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 that are 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. We also work on new types of multimodal AFM-based electrical imaging methods, and fun & useful things within the realm of SPM and laser spectroscopy.

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

Ambient condition surface potential measurement with 10 nm spatial resolution


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


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


We are actively seeking new group members and 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