Caffeine keeps physicists up at night. Particularly those concerned with the capacity of electrons to absorb energy. In a new study published in EPJ B, a Franco-Japanese team of physicists have used the caffeine molecule as a playground to test the effect of ionising radiation on its electrons as they approach excited states. Their model accounts for the ionisation phenomenon in electrons, which are in a site-specific, localised orbit in the caffeine molecule. The electron excitation leaves the door open to positive charge progression along a molecular backbone. Thomas Niehaus from Claude Bernard Lyon 1 University, France, and colleagues have now developed a method for quantifying this positive charge migration in line with the ultra-short laser impulse. The observed charge motion happens on an attosecond time scale charge rearrangements driven by nuclear motion.