SINGLE-MOLECULE OPTICAL SWITCHING OF TERRYLENE IN P-TERPHENYL

The controlled manipulation and switching of single atoms and molecule s raise the prospect of ultra-high-density data storage, Switching by motion of a single atom has been reported(1), and techniques of single -molecule optical detection and spectroscopy(2) in the condensed phase have been refined to a degree that allows the modification of the abs orption properties of a single chromophore(3). Light-induced jumps in single-molecule excitation frequencies have been reported(3-5), but in none of these cases could the process be controlled: the jumps varied from molecule to molecule, they were interrupted by spontaneous jumps , and the new excitation frequencies could not be identified unambiguo usly, Here we report light-induced reversible frequency jumps of singl e molecules of the aromatic hydrocarbon terrylene embedded in a partic ular site of a p-terphenyl host crystal(6) at temperatures of around 2 K. The changes in absorption frequency for different terrylene molecu les were identical (within 0.5%) for all samples studied, Thus we were able to switch single-molecule absorption lines in a controlled way b etween well-defined frequency positions.