Two-photon mapping of molecular orientations in hexaphenyl microrings

✍ Scribed by J. Beermann; C. Marquart; S. I. Bozhevolnyi

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 308 KB
• Volume: 1
• Category: Article
• ISSN: 1612-2011
• DOI: 10.1002/lapl.200410062

✦ Synopsis

Using a far-field second harmonic scanning
optical microscope with a tightly focused beam being incident
perpendicular to the surface, we have observed two-photon
luminescence from microrings consisting of organic hexaphenyl
molecules that form ringlike (diameter ≈ 5 μm),
≈ 500-nm-high and very thin (100-200 nm) structures, i.e.
form rings of nanoneedles. The molecular orientation in these rings
is determined from the ratio of two-photon induced luminescence
signals for mutually perpendicular polarized excitations. We find
that, in general, the molecular orientation follows the orientation
of a nanoneedle, so that the local angle between the molecule axis
and that of the nanoneedle is kept within some limits. Our modeling
indicate that the observed deviations can be related to the
influence of a limited spatial resolution of the microscope and
fluctuations in the nanoneedle orientation with respect to an ideal
ring structure.