Our group focuses on advancing nanoscale imaging and spectroscopy techniques to study
the chemical and physical properties of materials at the nanometer scale. Our current
focus is on deeply integrating atomic force microscopy (AFM) with advanced laser spectroscopy
techniques. We are innovating and utilizing AFM-based photothermal action spectroscopy
(AFM-IR) and scattering-type scanning near-field optical microscopy (s-SNOM) to study
a wide range of materials, including soft matter, photovoltaics, two-dimensional polariton
and quantum materials, catalytic nanostructures, and biomacromolecules. We are particularly
interested in exploring nanoscale phenomena inaccessible to conventional optical spectroscopy,
which is limited by Abbe’s diffraction limit in spatial resolution. We are especially
focused on combining time-domain two-dimensional infrared (AFM-2DIR) spectroscopy
with AFM photothermal action detection. We are actively developing AFM-based 2DIR
techniques to investigate light-matter interactions and energy transfer at material
interfaces. In addition to AFM-based infrared techniques, our group is developing
and refining Kelvin probe force microscopy (KPFM) to study nanoscale surface electrical
potential at material interfaces.
- Amirhossein Zahmatkeshsaredorahi, Ruben Millan-Solsona, Devon S. Jakob,
Liam Collins, and Xiaoji G. Xu “Kelvin probe force microscopy under ambient
conditions”; Nature Reviews Methods Primers, 5, 35, (2025)
- Qing Xie, Yu Zhang, Eli Janzen, James H. Edgar, and Xiaoji G. Xu “Atomic-force-
microscopy-based time-domain two-dimensional infrared nanospectroscopy”
Nature Nanotechnology, 19, 1108-1115 (2024)
- Le Wang, Haomin Wang, and Xiaoji G. Xu “Principle and Applications of Peak
Force Infrared Microscopy” Chemical Society Reviews, 51, 5268 - 5286 (2022)
- Haomin Wang, Joseph M. González-Fialkowski, Wenqian Li, Qing Xie, Yan Yu,
and Xiaoji G. Xu “Liquid-Phase Peak Force Infrared Microscopy for Chemical
Nano-imaging and Spectroscopy” Analytical Chemistry, 93, 7, 3567-3575 (2021)
- Devon S. Jakob, Haomin Wang, Guanghong Zeng, Daniel E. Otzen, Yong Yan,
and Xiaoji G. Xu “Peak Force Infrared – Kelvin Probe Force Microscopy”
Angewandte Chemie Int. Ed., 59, 16083 (2020)
- Devon S. Jakob, Haomin Wang, and Xiaoji G. Xu “Pulsed Force Kelvin Probe
Force Microscopy” ACS Nano, 14, 4, 4839-4848 (2020)
- Haomin Wang, Le Wang, Devon S. Jakob, and Xiaoji G. Xu “Tomographic and
Multimodal Scattering-Type Scanning Near-field Optical Microscopy with Peak
Force Tapping Mode” Nature Communications, 9:2005 (2018)
- Le Wang, Haomin Wang, Martin Wagner, Yong Yan, Devon S. Jakob and Xiaoji
G. Xu “Nanoscale Simultaneous Chemical and Mechanical Imaging via Peak
Force Infrared Microscopy” Science Advances, 3, 6, e1700255 (2017)
- Haomin Wang, Le Wang and Xiaoji G. Xu “Scattering-type Scanning Near-field Optical Microscopy with Low Repetition Rate Pulsed Light Source through Phase-domain Sampling” Nature Communications, 7:13212 (2016)
- Le Wang and Xiaoji G. Xu “Scattering Type Scanning Near-field Optical
Microscopy with Reconstruction of Vertical Interaction” Nature Communications,
6:8973 (2015).
For a full list of publications, please see here
2025, Richard Van Duyne Early Career Award in Experimental Physical Chemistry, ACS PHYS Division
2025, Danser Distinguished Faculty Chair in Chemistry, Lehigh University
2025, Senior Member, National Academy of Inventors
2021, Camille Dreyfus Teacher-Scholar Award, Camille and Henry Dreyfus Foundation
2020-2022, Class of ’61 Professorship, Lehigh University
2020, Sloan Research Fellowship, Alfred P. Sloan Foundation
2019, NSF CAREER, National Science Foundation
2018, Beckman Young Investigator, Arnold and Mabel Beckman Foundation