Laser Spectroscopy of Isolated Molecules and Systems: Structure, Dynamics and Analysis

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This proposal requests support to renew a Discovery Grant program that has made substantial progress in two areas of fundamental focus. (1) In work at an important interdisciplinary frontier between chemistry and physics, we have developed a novel supersonic beam methodology that employs pulsed lasers in multiresonant excitation sequences to create a quantum-state-selected frozen molecular Rydberg gas. This gas evolves to form a strongly coupled ultracold plasma. (2) Combining laser spectroscopy with multivariate signal processing, we have devised novel optical instrumentation and discerning interpretive tools that promise broad utility for the spectrochemical analysis and classification of complex materials. We now propose a program of pioneering new experiments and theoretical models in our ultracold plasma research that will use radiative emission and tomographic imaging to chart electronically nonadiabatic channels of intramolecular relaxation, and characterize the inelastic scattering dynamics by which the relaxation to the ultracold plasma state occurs. These measurements will create an unprecedented laboratory for the study of long-range collision physics in correlated many-body systems, with direct relevance to important questions concerned with warm dense matter, non-Fermi metals, coupled quantum wells and the technological production of high-brightness electron sources. We propose to advance significantly in our work at the frontier of analytical Raman and infrared spectroscopy by coupling novel instrument configurations to powerful new data mining and multivariate analysis strategies, with an eye to the classification of complex synthetic and biological materials. We will use machine learning strategies to draw telling characteristics from multivariate covariance models that link spectra to structural and functional properties. By means of target-directed feature selection, we will isolate signature sub-spectra that describe fundamental chemical variations responsible for excursions in the properties of complex materials. This research will yield new real-time spectrochemical classification methodologies with important analytical applications ranging from discerning industrial process-control to clinical diagnosis.