Angular distribution of laser-induced fluorescence emission of active dyes in scattering media

Abstract

Angular dependence of the intensity and the emissive wavelength of the laser-induced fluorescence emission in hybrid media (fluorophores+nanoparticles) are investigated using various TiO densities as guest nanoscatterers in the ethanolic solutions of the host Rd6G and coumarin 4 (C4) molecules. It is shown that the intensity of the scattered photons varies in terms of the detection angle. When the nanoscatterer density increases at a certain excitation energy, the angular anisotropy enhances. While the emissive wavelength exhibits the spectral shift in terms of the angular variation for Rd6G fluorophores, it remains invariant for C4-based suspension. In the former case, the emissive wavelength undergoes a spectral shift in terms of angular variation. Several factors such as the optical path length in the scattering media, the excitation volume, and the re-absorption events of the fluorescence emissions by the non-excited molecules strongly affect the spectral features. In fact, the density of the scatterers, the dye concentration, and the interplay between Stokes shift rate and the overlapping between absorption/emission spectra of the given fluorophores are taken into account as the major parameters to form the angular distribution.

UV random laser emission from flexible ZnO-Ag-enriched electrospun cellulose acetate fiber matrix

“…49 , in flat samples, shown theoretically and experimentally that the increment of scatterers concentration modifies the shape of excited region, from a cone at relative lower concentrations to a hemisphere at relative higher concentrations. Similar studies performed later by other groups in cylindrical samples 50,51 , showed that the angular distribution of far-field intensity of RL is oval in shape. Figure 5 showed that the distribution of the far-field intensity of our RL is oval too, being more intense in the direction perpendicular to the sample surface than in the edge direction.…”

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“…This has already been explained in detail regarding the LIF spectroscopy of dye solutions that confront significant self-absorption (e.g. Rhodamine 6G and Coumarin 7 with small Stokes shift 30 ).…”

LabVIEW virtual instrument for zone penetration studies in flow-based analytical systems

“…The VI has the potential to be used in other areas e. g. spectroscopy or chromatography. The examinations of the Stokes shift in fluorescence [32][33] or development of an expert system for simultaneous ion-chromatographic determination of ions in wide concentration ranges as found in highly mineralized waters 34 are the examples of studies that can also potentially profit from the VI. The developed software is available upon request from the authors.…”