Nanoplasmonics and surface enhanced spectroscopy

Enhancement of photoluminescence and extinction of light 
in Au nanoparticles/shellac-dye/Au film planar plasmonic cavity
Anastasiya V. Tomchuk,1 Oleg A. Yeshchenko,1 Viktor V. Kozachenko,1 Antonina P. Naumenko,1 Yuri L. Slominskii,2 Randall J. Knize,3 
Michael Haftel4,5 and Anatoliy O. Pinchuk4,5
1 Physics Department, Taras Shevchenko National University of Kyiv, 
64/13 Volodymyrska str., 01601 Kyiv, Ukraine 
E-mail: nastiona30@gmail.com
2 Institute of Organic Chemistry, National Academy of Sciences of Ukraine, 5 Murmanska str., Kyiv 02660, Ukraine
3 Laser Optics Research Center, Physics Department, US Air Force Academy, Colorado Springs, Colorado, 80840, USA
4 Department of Physics, University of Colorado at Colorado Springs, 
5 Center for Plasmonics, Nanophotonics, and Metamaterials, Colorado Springs, Colorado, 80918, USA
Effects of plasmonic gap mode formation due to coupling between metal nanoparticles and thin metal film separated by thin dielectric luminescent film-spacer (gap) have been studied by means of light extinction and photoluminescence in three-layer planar Au NPs monolayer / shellac-dye film / Au film nanostructure with spacer thickness varied in the range 8 – 47 nm. The 3-fold enhancement of light extinction and 90 nm red shift of the plasmon mode have been observed in extinction spectra. The 37-fold enhancement of dye photoluminescence and the significant (48 nm) red shift of dye photoluminescence band have been observed for Au NPs monolayer / shellac-dye film / Au film nanostructure in comparison with bare shellac-dye film for the spacer thickness of 8 nm. The decrease of the spacer thickness causes the increase of the enhancement factor of dye photoluminescence indicating the strengthening of the gap mode field. FDTD calculations of the dependence of the intensity of the field of gap mode on the gap thickness have demonstrated good quantitative agreement with experimental data that proves the key role of gap mode in the enhancement of the electromagnetic field in planar metal NPs monolayer / dielectric film / metal film plasmonic cavity nanostructures. The variation of the gap thickness provides the possibility to tune controllably the spectral position and enhancement factor of the light emission from the emitters located in the gap.