Luminescence lifetime components in quartz: influence of irradiation and annealing
- Authors: Chithambo, Makaiko L , Ogundare, F O
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6811 , http://hdl.handle.net/10962/d1004304
- Description: Pulsed optically stimulated luminescence measured from quartz under certain combinations of annealing and measurement temperature can be resolved into multiple lifetime components. We have studied the influence on these lifetime components of annealing temperature up to 900 °C, beta irradiation dose as high as 1700 Gy, and temperature of stimulation up to 200 °C. Although the time-resolved spectra from which the lifetimes are determined may be measured without heating between irradiation and measurement, a necessary protocol in steady-state optical stimulation applications, studies reported in this paper have been augmented with investigations on the effect of temperature and duration of preheating on the principal and secondary lifetimes. Luminescence spectra for measurements up to 200 Gy consist of a single lifetime but two components occur thereafter, both are independent of radiation dose. The principal lifetime of 35 μs is not affected by temperature of anneal whereas the secondary lifetime increases from 9 to 18 μs when the annealing temperature is changed from 600 to 900 °C. The dependence of both the principal and secondary luminescence lifetimes on measurement temperature can be explained by thermal quenching of the associated luminescence. However, the influence of irradiation, preheating, and annealing on the lifetimes can be explained with reference to an energy band scheme in which the primary mechanism in the processes leading up to luminescence emission is the change in concentration of holes at various luminescence centres caused by annealing.
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- Date Issued: 2009
Address to Convocation 1978
- Authors: Henderson, Derek Scott
- Subjects: Rhodes University -- Convocation
- Language: English
- Type: Text
- Identifier: vital:7364 , http://hdl.handle.net/10962/d1017244
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Physicochemical properties of a zinc phthalocyanine – pyrene conjugate adsorbed onto single walled carbon nanotubes
- Authors: Ogbodu, Racheal O , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7328 , http://hdl.handle.net/10962/d1020589
- Description: A conjugate between zinc monoamino phthalocyanine (ZnMAPc) and pyrene (Py) represented as ZnMAPc–Py (complex 3) was synthesized and characterized by various spectroscopic techniques and by elemental analysis. This manuscript also reports on the photochemical and photophysical properties of 3. This new compound exhibited higher triplet, fluorescence and singlet oxygen quantum yields in comparison to the phthalocyanine alone, hence showing the advantages of attaching pyrene to the Pc without breaking the conjugation. We also observed a decrease in photophysical parameters upon adsorbing the ZnMAPc–Py complex onto single walled carbon nanotubes (SWCNT). However, ZnMAPc–Py still generated some singlet oxygen when adsorbed onto SWCNT. , Original publication is available at http://dx.doi.org/10.1039/C3DT50335F
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Vice-Chancellor's address to new students 1976
- Authors: Henderson, Derek Scott
- Subjects: Rhodes University
- Language: English
- Type: Text
- Identifier: vital:7337 , http://hdl.handle.net/10962/d1017066
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