Tetyana Torchynska

By Tetyana Torchynska and Yuri Vorobiev

Part of the book: Advanced Biomedical Engineering

By Tetyana V. Torchynska

Part of the book: Fingerprints in the Optical and Transport Properties of Quantum Dots

By Tetyana V. Torchynska

Photoluminescence, its excitation power dependence, and Raman scattering spectra have been studied in CdSe/ZnS and CdSeTe/ZnS QDs for the nonconjugated states and after the QD conjugation to the anti-Interleukin-10, Human papilloma virus and Pseudo rabies virus antibodies. The QD bioconjugation to charged antibodies stimulates the “blue” energy shift of PL bands related to exciton emission in the CdSe or CdSeTe cores. The “blue” energy shift of PL spectrum in bioconjugated CdSe/ZnS QDs has been attributed to the electronic quantum confined effects stimulated by decreasing the effective QD size at its bioconjugation to charged antibodies. It was shown that the attachment of a charge deals with the antibody to the exterior shell of CdSe/ZnS QDs, leads to blocking away a fraction of core’s volume. The energy band diagrams of CdSeTe/ZnS QDs in the nonconjugated and bioconjugated states have been designed, which permit to explain the types of optical transitions in QDs and their transformations at the QD bioconjugation. It is shown that the change of energy band profile and the “blue” shift of QD energy levels, owing to the change of potential barrier at the QD surface, are the dominant reasons of PL spectrum transformation in the double core CdSeTe/ZnS QDs conjugated to charged antibodies. Better understanding the QD bioconjugation to specific antibodies is expected to produce the major advances in biology and medicine and can be a powerful technique for early medical diagnostics.

Part of the book: Quantum Dots

By Tetyana V. Torchynska and Brahim El Filali

ZnO nanocrystal (NC) films, prepared by electrochemical etching with varying the technological routines, have been studied by means of photoluminescence (PL), scanning electronic microscopy (SEM), energy dispersion spectroscopy (EDS), Raman scattering, and X ray diffraction (XRD) techniques. Raman and XRD studies have confirmed that annealing stimulates the ZnO oxidation and crystallization with the formation of wurtzite ZnO NCs. The ZnO NC size decreases from 250–300 nm down to 40–60 nm with increasing the etching time. Two PL bands connected with the near‐band edge (NBE) and defect‐related emissions have been detected. Their intensity stimulation with NC size decreasing has been detected. The NBE emission enhancement is attributed to the week quantum confinement and exciton‐light coupling with polariton formation in small ZnO NCs. The luminescence, morphology, and crystal structure of ZnO:Cu NCs versus Cu concentration have been investigated as well. The types of Cu‐related complexes are discussed using the correlation between the PL spectrum transformations and XRD parameters. It is shown that the plasmon generation in Cu nanoparticles leads to the surface enhanced Raman scattering (SERS) effect and to PL intensity increasing the defect‐related PL bands. The comparison of ZnO and ZnO:Cu NC emissions has been done and discussed.

Part of the book: Thin Film Processes