LAUSR

An optical cavity mixes molecular vibrations with light and changes chemical reactivity Polariton chemistry is an emerging field that explores whether the products and rates of chemical reactions can be controlled by placing a reaction mixture between a pair of mirrors (an optical cavity), allowing light to interact with the molecules through molecular vibrational excitation. In this setup, molecules absorb energy from the light and release it back to the cavity many times over. Despite recent demonstrations (1–3), the details of this phenomenon are poorly understood (4). On page 790 of this issue, Chen et al. (5) describe the molecular dynamics of iron pentacarbonyl [Fe(CO)5] in an optical cavity. By using ultrafast infrared spectroscopy with subpicosecond time resolution, the authors observed how the cavity affects the intramolecular energy dissipation and rearrangement of CO moieties around the Fe atom. The findings add to our understanding of how polariton chemistry might be used to perform molecular transformations that are intractable by conventional synthesis.