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The Influence of Interfacial Effects on the Photophysics of Rhodamine 6G Thin Films on a Poly(vinylidene fluoride) Surface
journal contribution
posted on 2017-02-14, 00:00 authored by Matthew Mullen, William B. EulerThe
spectral response of ultrathin films of rhodamine 6G (Rh6G)
cast onto polyvinylidenefluoride (PVDF) coated glass slides is studied
to investigate a perceived fluorescence emission enhancement. Varying
the thickness of the Rh6G layer (submonolayer to multiple layers)
on the PVDF layer revealed the existence of multiple Rh6G species
on the surface, similar to previous reports on glass. Excitation spectra
show that J-type excitons are not responsible for an emission enhancement.
Trends in the fluorescence emission intensity show that the surface
roughness of the PVDF layer prevents the Rh6G molecules from organizing
the way they would on a smooth glass surface. The PVDF surface roughness
preserves the emissive monomers and excited-state excimers of Rh6G
while reducing the self-quenching of aggregates. Coupled with this
is an internal reflection effect that causes light to be trapped between
the Rh6G/PVDF and PVDF/glass interfaces. This effect leads to multiple
absorption events, and thus more efficient use of the incident light.