Data for paper 'Timing the Escape of a Caged Electron'

Core-Hole Clock Spectroscopy Data for Ar@C60: Charge transfer is fundamentally dependent on the overlap of the orbitals comprising the transport pathway. This has key implications for molecular, nanoscale, and quantum technologies, for which delocalization (and decoherence) rates are essential figures of merit. Here, we apply the core hole clock technique – an energy-domain variant of ultrafast spectroscopy – to probe the delocalization of a photoexcited electron inside a closed molecular cage, namely the Ar 2p5 4s1 state of Ar@C60. Despite the lack of frontier orbital mixing in the ground configuration, almost 80% of the excited state density is found outside the buckyball due to the formation of a markedly diffuse hybrid orbital. Far from isolating the intracage excitation, the surrounding fullerene is instead a remarkably efficient conduit for electron transfer: we measure characteristic delocalization times of 6.5 ± 0.1 fs and ≲ 0.6 fs, respectively, for a 3D Ar@C60 film and a 2D monolayer on Ag(111).