In this article, the results of femtosecond three-pulse photon echo peak shift (3-PEPS) measurements are reported for a series of cadmium selenide core−shell semiconductor nanocrystals. The peak shift data were found to be highly dependent on the shell compositions and particle morphologies. The static inhomogeneity parameter was found to vary from 10 cm−1 for highly isotropic particles to 170 cm−1 for particles with a broad size distribution. We also discuss the high-frequency (≈212 cm−1) longitudinal optical (LO) phonon and the low-frequency (≈13−19 cm−1) longitudinal acoustic (LA) phonon modes (ω00) and how the damping times and frequencies also depend on the choice of capping material.

Scanning confocal time-resolved fluorescence imaging measurements have been performed on light-emitting conjugated polymer thin films cast from a range of solvents. We have observed inhomogeneities in the emission spectra and fluorescence decay profiles at various micrometer-sized regions within these films. Some regions are observed to exhibit longer fluorescence decay times and emission at shorter wavelengths than typically reported for such films. These regions are associated with nonaggregated polymer structures. Solvent effects on the photophysical properties of conjugated polymer films were also investigated. The dissimilarity of fluorescence lifetime distributions and emission spectra for films deposited from different solvents shows the diversity of the configurations within films and a dependence/memory of the polymer conformation on the solvent from which the film was cast.

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