Near-field imaging of organic nanofibres.

The optical near-field of orientated nanofibres of para-hexaphenyl was investigated by a combination of localized far-field ultraviolet excitation and scanning near-field fluorescence detection. Morphological inhomogeneities of the nanofibres together with selective incoupling into the near-field probe resulted in a detection sensitivity was dependent on individual nanoaggregates. Strongest near-field intensity and radiation into the far-field were observed at the crossing points of nanofibres. The near-field observation of a distance-dependent damping of the waveguiding along the nanofibres allowed us to determine the imaginary part of the dielectric function of the nanofibres, in quantitative agreement with far-field optical data.