Effects of substituents in polyvinylcarbazole structures on their optical properties

Absorption, photoluminescence, and photoluminescence excitation spectra of solutions and thin films of N-vinylcarbazole polymers and copolymers with various substituents directly on the carbazole moiety and on the polymer chain were studied comprehensively. Polymers that were used previously to develop polymer composites with polymethine dyes having photosensitivity over a broad spectral range including the visible and near-IR regions were selected for the studies

STM-induced light emission from thin films of perylene derivatives on the HOPG and Au substrates

We have investigated the emission properties of N,N'-diheptyl-3,4,9,10-perylenetetracarboxylic diimide thin films by the tunneling-electron-induced light emission technique. A fluorescence peak with vibronic progressions with large Stokes shifts was observed on both highly ordered pyrolytic graphite (HOPG) and Au substrates, indicating that the emission was derived from the isolated-molecule-like film condition with sufficient π-π interaction of the perylene rings of perylenetetracarboxylic diimide molecules. The upconversion emission mechanism of the tunneling-electron-induced emission was discussed in terms of inelastic tunneling including multiexcitation processes. The wavelength-selective enhanced emission due to a localized tip-induced surface plasmon on the Au substrate was also obtained

Degradation of quantum dots and change of their energy spectra in semimagnetic semiconductors under nuclear irradiation

Spreading of the potential profile for the charge carriers in quantum dots in binary semiconductors and the shift of the quantum levels for electrons, holes and excitons under the nuclear irradiation has been investigated. The spreading occurs because of the redistribution of atoms of different kinds between the barrier and quantum dot due to radiationenhanced diffusion. It is shown that in semimagnetic semiconductors (e.g. CdTe/(Cd, Mn)Te), in which a giant magnetic splitting of exciton levels exists, the redistribution of magnetic ions under irradiation causes significant increase in the splitting of exciton levels in a magnetic field in a quantum dot