H-G Rubahn | PubMed Health

PubMed2006

Nanofiber frequency doublers.

Nanoscaled, needle-shaped frequency doublers have been generated via self-assembled surface growth from functionalized quaterphenylene molecules with a designed large hyperpolarizability. The nanofiber frequency doublers exhibit very weak fluorescence centered around 430 nm but emit a strong, resonance-enhanced second-harmonic signal when excited with infrared 80 fs laser pulses. The frequency doublers are employed to correlate second-harmonic response and morphology via two-dimensional true second-harmonic images of individual nanoaggregates obtained with the help of a femtosecond laser scanning microscope.

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PubMed2004

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.

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