The photoexcitation energy transfer was studied in donor-acceptor systems (DA) formed from a mixture of the semiconductor polymer poly [2-methoxy-5- (2`-ethylhexyloxy) -1,4-phenylenevinylene] (MEH-PPV) with C60 fullerene and endohedral metallofullerene Ho@C82. A significant effect of the exciton migration between the polymer units on the quenching of MEH-PPV luminescence has been established. The Foerster radii of nonradiative energy transfer for the investigated DA systems are estimated. It is shown that the DA system formed using endohedral metallofullerenes is the most effective. Based on MEH-PPV, model photovoltaic cells with different doping levels C60 and Ho@C82 were formed. For the formed cells, the spectral sensitivity of the Photo-EMF and the kinetics of the increase in the Photo-EMF signal under pulsed irradiation were measured. The mobility of charge carriers in the studied polymer composites was estimated. It was found that a change in the concentration of endohedral metallofullerene within 1-2% allows you to change the effective mobility of free carriers of the polymer heterojunction.
The dynamics of oxygen consumption during photodynamic processes and its subsequent restoration in malignant tumors and healthy tissues of mice were studied in vitro by kinetics of long-term luminescence of xanthene dyes. It was shown that to estimate changes in tissue oxygen tension, specific type of delayed fluorescence can be used which caused by singlet-triplet annihilation of singlet oxygen and a sensitizer in triplet state. In tumors under pulse excitation of sensitizers, reversible quenching of delayed fluorescence was observed, which is associated with a decrease in the tissue oxygen tension during photodynamic processes. Method for visualizing the restoration of the initial oxygen level in tissues after photodynamic action is proposed.
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