Abstract

With the advent of Scanning Near-field Optical Microscopy (SNOM) ultra high resolution optical microscopy has attracted a large interest. One of the conceptually simplest configurations for reaching a nearly molecular resolution is replacing a physical aperture by a single molecule as a point-like source. In this talk we present optical images taken, for the first time, with a single molecule as a light source [1]. We use the method of single molecule spectroscopy in order to optically detect a single impurity molecule embedded in a weakly doped organic crystal cooled to T= 1.4K. The light from a narrow-band tunable ring dye laser at a wavelength around 580nm is used to excite a single terrylene molecule in a p-terphenyl crystal when the frequency of the laser matches that of the zero-phonon-line of the terrylene molecule. By using high quality spectral filters one blocks the residual excitation light and detects the red-shifted fluorescence with a very high signal-to-noise ratio. The natural-lifetime-limited linewidth of about 50MHz together with the well-defined location of such a molecule makes it a highly sensitive spectral and spatial probe for its environment. Moreover, compared to dye molecules commonly studied at room temperature, the problem of photostability is nearly negligible for our system. In previous experiments we have demonstrated how the optical intensity distribution in a standing wave can be mapped with great precision using a single molecule as a point-like detector [2].

© 2000 IEEE