Molecular Spectroscopy

Catalog description

It is said that there are more than nine million organic chemical compounds. If you add to this list, inorganic complexes, composite materials such as alloys, minerals, and intermediate species like radicals and transition states, the list becomes truly monstrous. Also, the number of properties that interest scientists and engineers is vast (although modest compared to the above). A fascinating aspect of science is that it reveals a small number of general principles that govern the huge number of substances and their reactivities and properties. One powerful tool in the chemist's toolbox is Spectroscopy, which allows us to identify and monitor molecules at stages prior, during, and post reaction. Spectroscopy has allowed chemists to generalize many aspects of molecular behavior in a wide assortment of environments, ranging from vacuum to physiological conditions. In this course, condensed-phase spectroscopy will be emphasized, and we will focus largely on how the tools of molecular spectroscopy can be used to describe interactions between molecules and their surroundings. These interactions can have broad chemical consequences, which include changing molecular polarizabilities and reaction energetics. Therefore, the outcomes of condensed-phase chemical processes are largely influenced by these molecule-surroundings interactions. In this context, we will address important questions of how solvents modify molecular spectroscopic signals, and how these changes can be used for understanding chemical processes. We will begin by describing the properties of electromagnetic radiation and the absorption and emission of light by molecules. In particular, we will introduce, discuss, and apply the concepts of eigenvalues, eigenfunctions, and superpositions of molecular electronic and vibrational states. We will demonstrate how these concepts can be used to predict spectra for isolated (i.e. gas-phase) molecules. We will then extend these concepts to understand how solvents and other environmental influences impact these spectra. Another focus of the course will include explanations of how specific experimental techniques, such as transient and photoluminescence pectroscopy, can be used to understand the efficiencies of specific chemical transformations (e.g. isomerization, electron and proton transfer, dissociation), which are central to reactions in chemical, biological, and materials environments. We will also discuss recent experimental advances that have expanded the spatial, temporal, and energy resolutions of spectroscopic measurements.