Radiative and non-radiative de-excitation of slow highly charged ions transmitted through freestanding single layer graphene

Slow highly charged ions interacting with a solid surface undergo an ultrafast charge exchange combined with a rapid electronic de-excitation within less than 10 fs. These processes involve capture of some 10 electrons, emission of at least some 10 additional electrons from the surface and radiative as well as non-radiative de-excitation of the ion. To investigate the branching ratio of radiative vs. non-radiative de-excitation we measured x-ray emission of highly charged Ar ions with two, one or no K-shell hole(s) when they are transmitted through a freestanding single layer of graphene.