Surface Plasmon Resonance with Electrospun Nanofibers on Gold Surface

In this paper we report new excitation method of surface plasmon polariton (SPP) at air/gold interface with electrospun nanofibers. Nanofibers of polyvinylpirrolidone were electrospun onto the surface of a gold film. The observations by scanning electron microscopy and optical microscopy indicated that the average diameters of the nanofibers were about 300 nm and average sizes of pores were about 30-40 μm. Optical response of the nanofibers on gold surface was investigated by polarized reflection absorption spectroscopy (RAS). The RAS spectrum with p-polarized light showed two absorption bands while the spectrum with s-polarized light only one band. One is a band at about 520 nm that also found in the spectrum with s-polarized light. Another is a broad band in the near-infrared region which found only with p-polarized light. The peak intensity of the latter band increases with increase of incident angle of the polarized light and the peak wavelength of the band shifted to longer wavelength. These responses suggested that SPP at air/gold interface was excited with the scattering light from the electrospun nanofibers. We also found that the peak wavelength of the absorption band in near-infrared region changed with the increase of the amount of the nanofibers. This may be due to the fact that the sizes of the pores on gold surface became smaller than the propagation length of SPP, which resulted in scattering and interference of SPP.