Raman scattering from single gold nanostars coated with self-assembled monolayers of 4-mercaptobenzoic acid is observed. The Raman signal can be detected without the need of forming particle aggregates or resonant electronic excitation of the analyte. A total Raman enhancement factor of ${10}^7$ for individual nanostars is estimated. These features make gold nanostars promising for Raman imaging in cells or cellular membranes.

Two–photon direct laser writing (DLW) lithography is limited in the achievable structure size as well as in structure resolution. Adding stimulated emission depletion (STED) to DLW allowed overcoming both restrictions. We now push both to new limits. Using visible light for two-photon DLW (780 nm) and STED (532 nm), we obtain lateral structure sizes of 55 nm, a Sparrow limit of around 100 nm and we present two clearly separated lines spaced only 120 nm apart. The photo-resist used in these experiments is a mixture of tri- and tetra-acrylates and 7-Diethylamino-3-thenoylcoumarin as a photo-starter which can be readily quenched via STED.