(Invited) Combined Single-Molecule Raman and Conductance Spectroscopies

Abstract

The nanoscale manipulation and characterization of individual molecules is necessary for understanding the intricacies of molecular structure which ultimately governs phenomena such as reaction mechanisms, catalysis, local effective temperatures, surface interactions, and charge transport phenomenon. Along these lines, the field of molecular-scale electronics has evolved tremendously in recent years: from the initial experiments claiming single-molecule conductance measurements to the development of robust and reproducible platforms that have begun providing a detailed understanding of the charge transport properties of these systems. It has now become possible to probe the chemical, structural, mechanical, and electrical properties of single-molecule devices to explore unique functional paradigms for applications. However, continued advances in in situ characterization of a molecular junction are needed to provide detailed information about the molecular configuration and its impact on the charge transport, reactions, and device behavior. Single-molecule conductance and Raman spectroscopies each provide unique perspectives into the behavior of molecular systems and reactions at the single-molecule level. In this talk we will discuss the development and implementation of system designed to simultaneously obtain conductance information and Raman spectra from a molecular junction to provide this information. This will include the development of a MEMS-based break junction system that allows facile integration with a Raman microscope to maximize the solid-angle and photon collection.This multi-dimensional information yields repeatable, self-consistent, verification of single-molecule resolution, and allows for detailed analysis of structural and configurational changes of the molecule in situ. We will discuss the correlation between single-molecule binding events and changes in Raman spectra (intensity, modes, etc.) and conductance to explore the possibility of obtaining single-molecule spectra from the molecule bound between two electrodes. We will further explore the utility of this system for in situ characterization of active single-molecule devices including electrically-active single-molecule switches and memory devices.