Quasi-free electron energy in supercritical carbon dioxide and water: A research program involving rural and first-generation STEM students

Cuny Queens College, Flushing NY

Investigators

Abstract

With this award, the Chemical Structure, Dynamics, and Mechanisms (CSDM-A) Program of the Division of Chemistry is supporting Professor Cherice M. Evans at CUNY - Queens College and Professor Gary L. Findley at the University of Louisiana-Monroe to undertake complementary experimental and theoretical studies of the role of solvent structure in important chemical reactions. Their work seeks improved understanding upon which to base better, more efficient, and less environmentally invasive chemical manufacturing and processing. It is congruent with the aims of sustainable chemistry, including the principles that the use of solvents should be made unnecessary wherever possible, and solvents should be innocuous when used. By involving graduate and undergraduate students from CUNY as well as undergraduates from Louisiana - Monroe (many of whom are from low-income families and are first generation college students), the work makes available exciting research opportunities intended not only to advance science, but to retain student interest and expand capabilities in STEM fields. Some of the research utilizes synchrotron facilities at the Center for Advanced Microstructures and Devices in Baton Rouge, LA, allowing all participating students to interact with scientists from a high caliber user facility, while introducing CUNY students to new aspects of United States culture in a Living/Learning community environment. The requirement that Monroe participants present their research results at Queens College ensures that these students will be exposed to a major urban environment -a first for many of these students. The research specifically focuses on solvation of quasi-free electrons as probes of the solvent structure in the target media across the broad temperature and density range represented by these solvents. The systems chosen for study include supercritical carbon dioxide, high temperature water, and supercritical water. These solvents are targeted because their solvation properties can be adjusted by small changes in temperature and pressure, potentially enabling product isolation and solvent purification in a single step. A free electron in solution makes an ideal probe of local solvent structure, and will help illuminate reactivity in these important media. Electrons with low energies are produced by field-enhanced photoemission from electrode surfaces in the solvent and the resulting current is detected with a second electrode. Experiments are being conducted at a new synchrotron facility at the Center for Advanced Microstructures and Devices in Baton Rouge, LA, and the resulting data are used to develop empirical models for the microscopic structure of the supercritical solvent systems.