Photodynamics of Gas‐Phase Pyruvic Acid Following Light Absorption in the Actinic Region
Lewis Hutton, Basile F. E. Curchod
Abstract
Abstract The photochemistry of pyruvic acid has received a large attention due to its relevance to atmospheric chemistry. Pyruvic acid is produced in the troposphere from both biogenic and anthropogenic sources and is a prototypical model for the family of ‐dicarbonyls. What makes the photochemistry of pyruvic acid particularly interesting from a gas‐phase perceptive is its expected decarboxylation upon sunlight absorption. The exact photodynamics leading to this release of CO 2 remains elusive. In this work, we used a combination of excited‐ and ground‐state ab initio molecular dynamics to unravel the possible mechanisms leading to the decarboxylation of pyruvic acid. Our calculations highlight the importance of a proton‐coupled electron transfer mechanism taking place in the first excited electronic state and triggering a nonadiabatic transfer of the molecule to the ground electronic state. The decarboxylation takes place in the ground‐electronic state with the concomitant formation of methylhydroxycarbene. We also calculate the photoabsorption cross‐section and wavelength‐dependent quantum yields for pyruvic acid, highlighting the limits of our theoretical formalism.