Second Harmonic Generation and Fluorescence of CMONS Dye Nanocrystals Grown in a Sol‐Gel Thin Film

Abstract

CMONS: an alternative to fluorescent probes? Nanocrystals of CMONS dye (see picture), about 100 nm in diameter, were grown in a sol-gel thin film. The authors selectively grew the non-centrosymmetric form in order to study the nanocrystals' nonlinear properties. Using scanning optical microscopy, the two-photon induced fluorescence and the second harmonic generation (SHG) signals. (shown) were simultaneously mapped. Time-resolved fluorescence spectroscopy on a single nanocrystal yielded an excited-state relaxation time that is about twenty times smaller than that of a microcrystal, taken as the reference for bulk. This can be explained by the photoinduced isomerization of the stilbene-like CMONS molecules localized at the surface of the nanocrystal.