Employing metal-alkanethiol-${\mathrm{C}}_{60}$ sandwich structures we studied the ${\mathrm{C}}_{60}$ exciton lifetime as a function of distance (1–3 nm) to a metal. Based on the order and compactness of the self-assembling thiol layer a uniform separation of ${\mathrm{C}}_{60}$ and metal is achieved. The ${\mathrm{C}}_{60}$ exciton lifetime is measured by pump and second harmonic probe spectroscopy. Even at distances as small as 1 nm classic damping mechanisms prevail, and no evidence for additional decay channels is obtained. For Au and Ag substrates we find a predominance of energy transfer to bulk and to surface, respectively.

• Received 2 June 1997

DOI:https://doi.org/10.1103/PhysRevLett.79.3246