Influence of Silver Colloid on Fluorescein Spectral Properties

D. Frąckowiaka, A. Balterb, J. Karolczakc and P. Siejaka aInstitute of Physics, Poznań University of Technology, Nieszawska 13A, 60-965 Poznań, Poland bInstitute of Physics, N. Copernicus University, Grudziądzka 5/7, 87-100 Toruń, Poland cFaculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland

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Received: 5 6 2006; Revised version: 17 7 2006;

In order to check if the observed earlier changes in fluorescence intensities of fluorescein solution due to the addition of colloidal suspension of silver are related to the generation of surface plasmon coupled emission, the steady state photothermal spectra and fluorescence decay times of such samples were measured. The Gaussian components of photoacoustic spectra for solutions with and without silver colloid addition were determined and compared with components of absorption and fluorescence excitation spectra of the same samples. The efficiencies of thermal and radiative deactivation of various samples were discussed. The fluorescence decay times measured at the wavelength of excitation not exhibiting the increase in photonic mode density depend only on the dye concentration. Decays exhibit changes as a result of silver addition with excitation in the region in which enhancement of fluorescence is observed. These changes are due not only to the change in the fluorescence yield generated by interactions with plasmons but also to those in thermal deactivation of the sample related to the colloid presence.

DOI: 10.12693/APhysPolA.110.451 PACS numbers: 33.20.-t, 33.20.Kf, 33.50.-j