Conformer-Specific Photochemistry Imaged in Real Space and Time

Uses gas-phase MeV ultrafast electron diffraction to directly image the photochemical ring-opening of a specific α-phellandrene conformer, confirming Woodward–Hoffmann selection rules with femtosecond time resolution.

• Distinguishes conformational isomers in a reaction — a capability that most time-resolved experimental methods lack.
• Directly observes the transformation of a specific α-phellandrene conformer into the product isomer predicted by the Woodward–Hoffmann rules.
• Quantitative agreement with nonadiabatic quantum molecular dynamics simulations, providing detailed insight into how conformation influences reaction timescale and quantum efficiency.