Spectroscopic characterization of the structural dynamics of photoexcited metalloporphyrins
Date
2018
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Publisher
University of Delaware
Abstract
Understanding the behavior of molecular excited states is critical to inform the design of photochemical reactions. Applications ranging from solar energy conversion to medicinal photochemistry rely on chemical reactions that are initiated by photoexcited molecules. Complete characterization of excited-state dynamics includes the description of electronic and structural contributions. In this work, the structural dynamics of several metalloporphyrin systems are investigated after photoexcitation. Metalloporphyrins are widely used in photochemical schemes due to their desirable optical properties, and their excited-state behavior is relevant for many applications. Transient absorption, pump-degenerate four-wave mixing, and X-ray transient absorption spectroscopies were the primary methods used to study the ultrafast processes accompanying excitation. Information was provided on electronic-vibrational coupling, vibrational coherence, structural reorganization, and solvent-chromophore interactions taking place in the excited-states of metalloporphyrins. Highlights include the identification of excited-state metal ligation and the probing of adiabaticity in heterogeneous electron transfer. An inconspicuous measurement artifact is also identified and characterized. Descriptions are included of experimental methods and instrumental systems that were developed to facilitate the measurement of ultrafast vibrational dynamics on increasingly complex systems.
Description
Keywords
Pure sciences, Photoexcited metalloporphyrins, Spectroscopic characterization, Structural dynamics