We report the ability to spectrally resolve excited-state ensembles of pyranine (Py) utilizing nanometer-thick metal films as a low-cost analytical tool. Surface plasmon coupling allows to mitigate the effect of spectral broadening that is responsible for blurring the emission spectrum at room temperature, a situation common in conventional fluorescence spectroscopy. The approach is especially useful in the case when several excited-state species are present. Fluorescence emission from closely located protonated, deprotonated, and excimer species of Py couple into surface plasmons and are easily separated and observed with 11–14 fold intensity enhancements. Furthermore, the ultranarrowband photon-sorting of emission from microenvironments in a multispecies system is performed in this study using instruments that are readily available in most laboratories without employing any deconvolution procedure and/or additional dispersive optics.
© 2009 Optical Society of America
Original Manuscript: June 9, 2009
Revised Manuscript: September 3, 2009
Manuscript Accepted: September 4, 2009
Published: September 22, 2009
Ramamurthy Sai Sathish, Yordan Kostov, and Govind Rao, "Spectral resolution of molecular ensembles under ambient conditions using surface plasmon coupled fluorescence emission," Appl. Opt. 48, 5348-5353 (2009)