Reaction Tomography - Atomically Resolved Imaging of Chemical Transformations with Molecular Functionalized SPM Tips

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Fischer at the University of California, Berkeley, is developing atomically resolved imaging techniques that enhance the analytical tools available to image, manipulate, and spectroscopically characterize the reactivity and self-assembly of molecular structures on surfaces. This research program overcomes challenges faced in the application of atomic-resolution scanned probe techniques, and makes these techniques both more accessible to researchers and more capable of answering significant scientific questions regarding the chemical composition, electronic structure, and reactivity of molecular systems. The tools and techniques developed are not only be able to identify unknown compounds with single-atom resolution, but have an impact on all nanoscience areas that require precise knowledge of atomic-scale processes. This includes the development of new applications that benefit society in the areas of energy research, molecular-scale electronics, molecular recognition, and sensor technology. The interdisciplinary science that lies at the core of this project is introduced to students at all levels, from K-12, across the undergraduate to the graduate level via integrated research and educational components. Undergraduate students recruited from California State University East Bay as part of a summer training program in synthetic organic chemistry contribute to the establishment of a publicly accessible library for atomically-resolved images of adsorbed molecular systems that serve as a resource for K-12 and undergraduate educators. The goal of this research project is to develop scanned probe microscopy (SPM) techniques capable of resolving individual atoms and molecular bonding configurations with higher spatial resolution and elemental specificity than previously possible. A new class of molecular probe tips is derived from multipodand chelating ligands that selectively bind to low-coordinated transition metals lining the apex of electrically etched SPM tips. These chemically engineered probe tips feature electronically and vibrationally tunable apex configurations capable of inducing element specific covalent or non-covalent interactions with molecular adsorbates on surfaces. The project focuses on overcoming three significant challenges currently faced by single-molecule SPM techniques ? achieving atomic resolution in non-planar molecular structures, achieving atomically-resolved elemental composition, and achieving distortion-free characterization of bond strengths and their order. The SPM techniques developed herein address key challenges at the forefront of single molecule imaging, pave the way for the discovery and elucidation of surface facilitated reaction mechanisms, and provide an unprecedented detailed insight into the most elemental steps of common chemical transformations. 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.