SINGLE-MOLECULE SPECTROSCOPY IN HE GAS-USING A HIGHLY EFFICIENT MIRROR ARRANGEMENT

We present a new experimental setup for single molecule spectroscopy u sing a high efficient mirror arrangement with a geometrical efficiency of 0.77. Signal-to-noise (S/N) ratios up to 90 for single pentacene m olecules in a p-terphenyl crystal demonstrate that increasing the dete ction efficiency improves the S/N ratio if the detection geometry ensu res a strong stray light suppression. This is realized by the presente d mirror arrangement. The experiments were done in a He contact gas cr yostat, which is able to work below the lambda point. Temperatures dow n to 1.7 K at the sample were obtained. (C) 1997 American Institute of Physics.