High-Accuracy Thermochemistry with Threshold and Imaging Photoelectron Photoion Coincidence Spectroscopy

University Of The Pacific, Stockton CA

Investigators

Abstract

Through this award, funded by the Chemical Structure, Dynamics, and Mechanisms - A Program of the Division of Chemistry, Prof. Bálint Sztáray from the University of the Pacific, will characterize the thermochemistry of molecules and radicals that have combustion or atmospheric relevance. Using Photoelectron Photoion Coincidence Spectroscopy, significant improvements will be offered to three of the most important parameter sets in combustion and atmospheric models: accurate experimental thermochemical data, reaction rates, and energy distributions. The experiments will be conducted both on the lab-based instrument at the University of the Pacific, which will receive an upgrade of a new ion velocity map imaging setup, and on the Imaging Photoelectron Photoion Coincidence Spectroscopy endstation at the Swiss Light Source synchrotron. Combining experimental ion fragmentation and velocity distribution data with high-level quantum chemical calculations, advances will be offered in the understanding of statistical rate and energy distribution theories to improve the kinetics modeling tools used in combustion and atmospheric models. Energy is arguably the most important physical quantity, affecting almost every aspect of physical, chemical and biological processes. Chemical changes in the structure of molecules are almost invariably accompanied by changes in the energy, determining which chemical reactions are possible. As the primary purpose of combustion processes is to extract energy from chemical systems, characterizing the energy content of the various molecules and fragments involved in combustion is the foundation on which predictive models can be built. Thermochemistry, the study of the role of energy in chemical processes, has gone through transformative changes in the last decade, partly due to advances in computational methods and party due to new holistic models in which energy changes in remotely related systems are connected in a complex web of energy relationships. Computational methods in the past few years have approached and even exceeded experimental accuracy and they need new and more accurate experimental data to be tested against. The experimental methods used in this research will provide some of the most accurate numbers on a wide variety of systems that are involved in combustion or atmospheric processes.