Now showing 1 - 2 of 2
  • Publication
    Photophysical studies of CdTe quantum dots in the presence of a zinc cationic porphyrin
    The photophysical properties of 2.3 nm thioglycolic acid (TGA) coated CdTe quantum dots (QDs) prepared by a reflux method have been studied in the presence of cationic meso-tetrakis(4-N-methylpyridyl) zinc porphyrin (ZnTMPyP4). Addition of the CdTe QDs to the porphyrin in H2O results in a marked red-shift and hypochromism in the porphyrin absorption spectrum, indicative of a non-covalent binding interaction with the QD surface. Only low equivalents of the quantum dot were required for complete quenching of the porphyrin fluorescence revealing that one quantum dot may quench more than one porphyrin. Similarly addition of porphyrin to the quantum dot provided evidence for very efficient quenching of the CdTe photoluminescence, suggesting the formation of CdTe'porphyrin aggregates. Definitive evidence for such aggregates was gathered using small angle X-ray spectroscopy (SAXS). Ultrafast transient absorption data are consistent with very rapid photoinduced electron transfer (1.3 ps) and the resultant formation of a long-lived porphyrin species.
      450Scopus© Citations 25
  • Publication
    Synthesis and spectroscopic studies of chiral CdSe quantum dots
    Using microwave irradiation, water soluble, optically active, penicillamine (Pen) capped CdSe nanocrystals with broad spectral distribution (430-780 nm) of photoluminescence have been produced and studied by a range of instrumental techniques including absorption, circular dichroism and both steady state and time resolved photoluminescence spectroscopy. The photoluminescence of these nanocrystals is attributed to emission from surface defect states. The decay of the excited state in the nanosecond region, which can be analysed as a triple exponential, depends strongly on the emission wavelength selected, but only weakly on the excitation wavelength.
      562Scopus© Citations 79