Electron-paramagnetic resonance and photoluminescence study of Si nanocrystals-photosensitizers of singlet oxygen molecules

2006 ◽  
Vol 352 (9-20) ◽  
pp. 1156-1159 ◽  
Author(s):  
E.A. Konstantinova ◽  
V.A. Demin ◽  
A.S. Vorontzov ◽  
Yu. V. Ryabchikov ◽  
I.A. Belogorokhov ◽  
...  
2011 ◽  
Vol 15 (02) ◽  
pp. 118-121 ◽  
Author(s):  
Lawrence J. Berliner ◽  
Helmut Görner ◽  
Heinz-Peter Schuchmann

Singlet molecular oxygen produced in the presence of 2,2,6,6-tetramethyl-4-piperidone (TMPD) in 1,4-dioxan, by boron subphthalocyanine chloride as the sensitizer, was monitored by Electron Paramagnetic Resonance (EPR) via the oxidation of TMPD to the corresponding aminoxyl radical. This radical product is formed in low yields along the singlet oxygen pathway. A kinetic analysis of the process allows one to understand the reasons behind this, while affording more accurate quantitative insights into the mechanistic details. A crucial aspect of this reaction system, which explains the low aminoxyl radical yields along the singlet oxygen pathway, is the disappearance of the sensitizer triplet state in a reaction with TMPD, which has a rate constant of 1 × 109 M-1.s-1.


2010 ◽  
Vol 75 (7) ◽  
pp. 965-973 ◽  
Author(s):  
Svetlana Jovanovic ◽  
Zoran Markovic ◽  
Duska Kleut ◽  
Vladimir Trajkovic ◽  
Branka Babic-Stojic ◽  
...  

In this paper, the results of the synthesis and characterization of higher fullerene-based colloids is presented. The generation of singlet oxygen 1O2 (1?g) by fullerene water-based colloids (nC60, nC70 and nC84) was investigated. It was found by electron paramagnetic resonance spectroscopy that the generation of singlet oxygen was the highest by the nC84 colloid. The amplitude of the electron paramagnetic resonance (EPR) signal was two orders of magnitude higher than the amplitude of the EPR signals which originated from nC60 and nC70. The surface morphology and the structure of the particles of the water-based colloids were investigated by atomic force microscopy (AFM). The AFM study showed that the average size of the nC60, nC70 and nC84 were 200 nm, 80 nm and 70 nm, respectively. In addition, the particle size distribution of the nC60, nC70 and nC84 colloids was determined by dynamic light scattering (DLS) measurements.


1999 ◽  
Vol 59 (4) ◽  
pp. 2773-2782 ◽  
Author(s):  
J. D. Carey ◽  
R. C. Barklie ◽  
J. F. Donegan ◽  
F. Priolo ◽  
G. Franzò ◽  
...  

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