Nanoscale Chemical Imaging via Optical Transduction in Atomically-Precise Model Systems

About This Grant

With the support of the Chemical Measurement and Imaging Program in the Division of Chemistry, Professors Andrew J. Mannix and Felipe Homrich da Jornada of Stanford University will develop new microscopy and quantum simulation tools to directly observe how individual chemical bonds respond to light absorption at the atomic scale. When materials absorb light, they may enter an excited state that alters their structure and electronic properties, influencing performance in technologies such as digital cameras, night vision systems, solar cells, light-emitting diodes, and quantum sensors. However, directly visualizing these structural changes at the level of individual atoms has remained out of reach. This project will advance a new form of photo-induced force microscopy capable of mapping where light is absorbed and how atomic bonds deform in response, enabling direct imaging of excited-state structural changes in molecules and semiconductor materials. By comparing these measurements with advanced quantum simulations, the research will help guide the design of materials that more efficiently capture or emit light. These advances could benefit imaging, sensing, energy, and quantum technologies. The project will also contribute to workforce development by training graduate and undergraduate students in experimental and computational methods, creating instructional materials for chemistry and materials science courses, and participating in public outreach. Methods and results will be disseminated through open-access publications, enabling widespread implementation using existing nanoscale imaging platforms. More specifically, this project will develop a novel implementation of photo-induced force microscopy (PiFM) that operates at cryogenic temperatures and in ultra-high vacuum, enabling sub-angstrom spatial resolution of optically induced forces in individual molecules and atomically thin materials. The technique will combine tip-enhanced optical excitation with mechanical force detection via a quartz tuning fork sensor to directly measure bond-level structural distortions following electronic excitation. These measurements will be quantitatively compared to excited-state force maps generated by ab initio quantum simulations based on many-body perturbation theory and real-space force projection. This integrated experimental–theoretical framework will enable chemically specific analysis of how light absorption perturbs bonding configurations, charge localization, and vibrational coupling. Initial studies will target benchmark chromophores such as pentacene and perylenes, on both metal substrates (e.g., Au) and weakly screening van der Waals substrates (e.g., graphene and hexagonal boron nitride). These platforms will enable targeted investigation of the chemical origins of substrate hybridization and plasmonic enhancement, and how these factors shape the photoinduced force (PiF) spectra. By revealing the atomic-scale mechanisms of excited-state relaxation and reorganization, the project will advance fundamental understanding of excited-state chemistry and light–matter interactions in both molecular and solid-state systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.