Single molecule detection and underwater fluorescence imaging with cantilevered near-field fiber optic probes

This is the published version, also available here: http://dx.doi.org/10.1063/1.121505.Tapping-mode near-field scanning optical microscopy (NSOM) employing a cantilevered fiber optic probe is utilized to image the fluorescence from single molecules and samples in aqueous environments. The single molecule fluorescenceimages demonstrate both the subdiffraction limit spatial resolution and low detection limit capabilities of the cantilevered probe design. Images taken as a function of tip oscillation drive amplitude reveal a degradation in the resolution as the amplitude is increased. With all cantilevered probes studied, however, a minimum plateau region in the resolution is reached as the drive amplitude is decreased, indicating that the tapping mode of operation does not reduce the optical resolution. Images of fluorescently dopedlipid films illustrate the ability of the probe to track small height changes (