Ultrafast studies of the relaxation of photoinduced hot electrons in fullerene and endohedral fullerene molecules are valuable in organic photovoltaics . Also, extreme light confinement through plasmon excitation in these molecules, that are prototypes for families of smaller nanosystems, enables plasmon-induced electronic processes, such as, in catalytic reactions or as controllable nanoscale slow-electron sources . With the possibility of easy production of C60 and with remarkable advances in synthesis methods of endohedral C60 in gas phase, in solution or as thin films , these systems have recently caught particular attentions. For instance, they render eminent natural laboratories to probe both the relaxation process upon a mid-UV photon absorption and the giant plasmonic electron emission process upon an extreme-UV photon absorption. The former occurs in a femtosecond timescale due to the importance of the electron-phonon nonadiabatic coupling, while the latter plays out at a much faster attosecond speed due to the dominant collective electronic coherence. I will show results of our recent computational studies of both these processes that elicited novel effects [4, 5]. The relaxation study can inspire ultrafast transient absorption and/or time-resolved photoelectron spectroscopic experiments. The plasmonic emission time delay results, on the other hand, has already been brilliantly tested by attosecond photoemission chronoscopic measurements.
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