This research was supported by the U.S. Department of Energy’s (DOE) Office of Basic Energy Sciences, Chemical Sciences Division. Pacific Northwest National Laboratory is operated for DOE by Battelle under Contract No. DE-AC06-76RLO 1830.
Physical Review Letters
Fluorescence microscopy -- Methodology, Fluorescence
We present a new scheme for near-field fluorescence imaging using a metal tip illuminated with femtosecond laser pulses of proper polarization. The strongly enhanced electric field at the metal tip (ap15 nm end diameter) results in a localized excitation source for molecular fluorescence. Excitation of the sample via two-photon absorption provides good image contrast due to the quadratic intensity dependence. The spatial resolution is shown to be better than that of the conventional aperture technique. We used the technique to image fragments of photosynthetic membranes, as well as j-aggregates with spatial resolutions on the order of 20 nm.
Sanchez, E. J., Novotny, L. L., & Sunney Xie, X. X. (1999). Near-field fluorescence microscopy based on two-photon excitation with metal tips. Physical Review Letters, 82(20), 4014-4017.