Ultrafast experiments capture speed-of-light excitation delay as photon travels across H2
Photon excites one end of the molecule first, and then the other end 247 zeptoseconds later
Scientists in Germany have measured a zeptosecond time delay between a photon hitting a dihydrogen molecule and its electrons being ejected. They say this ‘birth-time delay’ corresponds to the time taken for the photon to travel the length of the molecule.