Optically stimulated luminescence and spectral emission features of radioluminescence and thermoluminescence of natural kunzite:
- Alatishe, M A, Ogundare, F O, Folley, Damilola E, Chithambo, Makaiko L, Chikwembani, S
- Authors: Alatishe, M A , Ogundare, F O , Folley, Damilola E , Chithambo, Makaiko L , Chikwembani, S
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160478 , vital:40449 , https://doi.org/10.1016/j.radmeas.2020.106457
- Description: Features of luminescence optically stimulated from natural kunzite using 470 nm blue light are reported. Preparatory measurements of its X-ray excited radioluminescence and thermoluminescence show that the sample has two main bands centered at 360 nm and 600 nm. The optically stimulated luminescence discussed in this report was monitored in the UV region and is presumed to be the same 360 nm emission that appears in the radioluminescence and thermoluminescence spectra. The glow curve shows at least three peaks at 74, 202, 432 oC for heating at 1 oC and the third one is a composite of two. Only the first two peaks are deduced to contribute most of the optically stimulated luminescence.
- Full Text:
- Date Issued: 2020
- Authors: Alatishe, M A , Ogundare, F O , Folley, Damilola E , Chithambo, Makaiko L , Chikwembani, S
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160478 , vital:40449 , https://doi.org/10.1016/j.radmeas.2020.106457
- Description: Features of luminescence optically stimulated from natural kunzite using 470 nm blue light are reported. Preparatory measurements of its X-ray excited radioluminescence and thermoluminescence show that the sample has two main bands centered at 360 nm and 600 nm. The optically stimulated luminescence discussed in this report was monitored in the UV region and is presumed to be the same 360 nm emission that appears in the radioluminescence and thermoluminescence spectra. The glow curve shows at least three peaks at 74, 202, 432 oC for heating at 1 oC and the third one is a composite of two. Only the first two peaks are deduced to contribute most of the optically stimulated luminescence.
- Full Text:
- Date Issued: 2020
Thermoluminescence of SrAl2O4: Eu2+, Dy3+: kinetic analysis of a composite-peak
- Chithambo, Makaiko L, Wako, A H, Finch, A A
- Authors: Chithambo, Makaiko L , Wako, A H , Finch, A A
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124157 , vital:35571 , https://doi.org/10.1016/j.radmeas.2016.12.009
- Description: The kinetic analysis of thermoluminescence of beta-irradiated SrAl2O4:Eu2+,Dy3+ is reported. The glow-curve is dominated by an apparently-single peak. It has been demonstrated using a number of tests including partial dynamic-heating, isothermal heating, phosphorescence and, the effect of fading, that the peak and the glow-curve consists of a set of closely-spaced peaks. In view of the peak being complex, its first few components were abstracted and analysed and for comparison, the peak was also analysed assuming it is genuinely single.
- Full Text: false
- Date Issued: 2017
- Authors: Chithambo, Makaiko L , Wako, A H , Finch, A A
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124157 , vital:35571 , https://doi.org/10.1016/j.radmeas.2016.12.009
- Description: The kinetic analysis of thermoluminescence of beta-irradiated SrAl2O4:Eu2+,Dy3+ is reported. The glow-curve is dominated by an apparently-single peak. It has been demonstrated using a number of tests including partial dynamic-heating, isothermal heating, phosphorescence and, the effect of fading, that the peak and the glow-curve consists of a set of closely-spaced peaks. In view of the peak being complex, its first few components were abstracted and analysed and for comparison, the peak was also analysed assuming it is genuinely single.
- Full Text: false
- Date Issued: 2017
Temperature-dependence of time-resolved optically stimulated luminescence and composition heterogeneity of synthetic α-Al2O3: C
- Chithambo, Makaiko L, Costin, G
- Authors: Chithambo, Makaiko L , Costin, G
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124172 , vital:35573 , https://doi.org/10.1016/j.jlumin.2016.10.038
- Description: The relationship of pulse-width, lifetime and measurement temperature in describing intensity of time-resolved luminescence optically stimulated at 470 nm from α-Al2O3:C is reported. The change of luminescence intensity with stimulation temperature is discussed in terms of the signal integrated over a complete time-resolved luminescence spectrum or in terms of ratios of the signal emitted either during or after pulsed stimulation to the total signal obtained per spectrum. The temperature-induced change in these parameters depends on whether the pulse-width is less or more than the luminescence lifetime. This is because the lifetime in α-Al2O3:C varies with measurement temperature. We have developed and applied new models to distinguish thermal assistance from different traps and to use this information as an additional means to analyse thermal quenching by using the luminescence intensity integrated from time-resolved spectra. Using a model based on use of the throughput, the activation energy for thermal assistance was determined for the shallow trap as 0.054±0.001 eV and as 0.53±0.03 eV for the main trap. The activation energy for thermal quenching was then evaluated using luminescence yield during the pulse as 1.09±0.01 eV and as 1.12±0.01 eV using the throughput after the pulse. Using the new analytical method based on integrated intensity, the activation energy for thermal quenching was found as 1.00±0.07 eV. These values are self-consistent and show that the methods for analyzing temperature-induced changes in intensity and the attendant thermal effects, such as thermal assistance can be successfully applied. We have also reported a general mathematical model that accounts for the temperature-dependence of time-resolved luminescence from α-Al2O3:C. The luminescence study was complemented by investigation of the phase and composition heterogeneity of the samples.
- Full Text: false
- Date Issued: 2017
- Authors: Chithambo, Makaiko L , Costin, G
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124172 , vital:35573 , https://doi.org/10.1016/j.jlumin.2016.10.038
- Description: The relationship of pulse-width, lifetime and measurement temperature in describing intensity of time-resolved luminescence optically stimulated at 470 nm from α-Al2O3:C is reported. The change of luminescence intensity with stimulation temperature is discussed in terms of the signal integrated over a complete time-resolved luminescence spectrum or in terms of ratios of the signal emitted either during or after pulsed stimulation to the total signal obtained per spectrum. The temperature-induced change in these parameters depends on whether the pulse-width is less or more than the luminescence lifetime. This is because the lifetime in α-Al2O3:C varies with measurement temperature. We have developed and applied new models to distinguish thermal assistance from different traps and to use this information as an additional means to analyse thermal quenching by using the luminescence intensity integrated from time-resolved spectra. Using a model based on use of the throughput, the activation energy for thermal assistance was determined for the shallow trap as 0.054±0.001 eV and as 0.53±0.03 eV for the main trap. The activation energy for thermal quenching was then evaluated using luminescence yield during the pulse as 1.09±0.01 eV and as 1.12±0.01 eV using the throughput after the pulse. Using the new analytical method based on integrated intensity, the activation energy for thermal quenching was found as 1.00±0.07 eV. These values are self-consistent and show that the methods for analyzing temperature-induced changes in intensity and the attendant thermal effects, such as thermal assistance can be successfully applied. We have also reported a general mathematical model that accounts for the temperature-dependence of time-resolved luminescence from α-Al2O3:C. The luminescence study was complemented by investigation of the phase and composition heterogeneity of the samples.
- Full Text: false
- Date Issued: 2017
Relative features of the principal and secondary luminescence lifetimes in quartz
- Chithambo, Makaiko L, Ogundare, F O
- Authors: Chithambo, Makaiko L , Ogundare, F O
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125821 , vital:35820 , https://doi.10.1002/pssc.200673721
- Description: Quartz is a common natural mineral with properties that make it amenable for application in radiation dosimetry using luminescence methods [1]. The luminescence properties of quartz including its sensitivity and luminescence lifetimes undergo notable changes when the quartz is annealed, and in particular, near its phase inversion temperatures of 573 and 867 oC [2, 3]. The physical processes leading up to the emission of luminescence in quartz may be investigated using time-resolved optical stimulation. The aim of this method is to separate in time the stimulation and emission of luminescence to enable measurement of time-resolved luminescence spectra which may be resolved into associated lifetimes, defined in this sense as the delay between stimulation and emission of luminescence [4, 5]. A number of such studies show that annealing defines the detailed distribution of lifetimes with measurement temperature as well as the irradiation-dependent characteristics of the lifetimes [3, 6]. In particular, it was noted [3] that spectra measured at certain temperatures could be accurately resolved into more than one component, a scenario that pointed to the possibility of involvement of multiple luminescence centers in the emission of luminescence from quartz. The aim of this work is to build on the findings described, specifically to study the influence of measurement temperature and irradiation on the principal and subsidiary luminescence lifetimes in natural quartz.
- Full Text:
- Date Issued: 2017
- Authors: Chithambo, Makaiko L , Ogundare, F O
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125821 , vital:35820 , https://doi.10.1002/pssc.200673721
- Description: Quartz is a common natural mineral with properties that make it amenable for application in radiation dosimetry using luminescence methods [1]. The luminescence properties of quartz including its sensitivity and luminescence lifetimes undergo notable changes when the quartz is annealed, and in particular, near its phase inversion temperatures of 573 and 867 oC [2, 3]. The physical processes leading up to the emission of luminescence in quartz may be investigated using time-resolved optical stimulation. The aim of this method is to separate in time the stimulation and emission of luminescence to enable measurement of time-resolved luminescence spectra which may be resolved into associated lifetimes, defined in this sense as the delay between stimulation and emission of luminescence [4, 5]. A number of such studies show that annealing defines the detailed distribution of lifetimes with measurement temperature as well as the irradiation-dependent characteristics of the lifetimes [3, 6]. In particular, it was noted [3] that spectra measured at certain temperatures could be accurately resolved into more than one component, a scenario that pointed to the possibility of involvement of multiple luminescence centers in the emission of luminescence from quartz. The aim of this work is to build on the findings described, specifically to study the influence of measurement temperature and irradiation on the principal and subsidiary luminescence lifetimes in natural quartz.
- Full Text:
- Date Issued: 2017
Time-resolved luminescence from quartz: an overview of contemporary developments and applications
- Chithambo, Makaiko L, Pagonis, Vasilis, Ankjærgaard, Christina
- Authors: Chithambo, Makaiko L , Pagonis, Vasilis , Ankjærgaard, Christina
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124743 , vital:35658 , https://doi.org/10.1016/j.physb.2015.10.014
- Description: Time-resolved optical stimulation of luminescence has become established as a key method for measurement of optically stimulated luminescence from quartz, feldspar and α-Al2O3:C, all materials of interest in dosimetry. The aim of time-resolved optical stimulation is to separate in time the stimulation and emission of luminescence. The luminescence is stimulated from a sample using a brief light pulse and the emission monitored during stimulation in the presence of scattered stimulating light or after pulsing, over photomultiplier noise only. Although the use of the method in retrospective dosimetry has been somewhat limited, the technique has been successfully applied to study mechanisms in the processes leading up to luminescence emission. The main means for this has been the temperature dependence of the luminescence intensity as well as the luminescence lifetimes determined from time-resolved luminescence spectra. In this paper we review some key developments in theory and applications to quartz including methods of evaluating lifetimes, techniques of evaluating kinetic parameters using both the dependence of luminescence intensity and lifetime on measurement temperature, and of lifetimes on annealing temperature. We then provide an overview of some notable applications such as separation of quartz signals from a quartz–feldspar admixture and the utility of the dynamic throughput, a measure of luminescence measured as a function of the pulse width. The paper concludes with some suggestions of areas where further exploration would advance understanding of dynamics of luminescence in quartz and help address some outstanding problems in its application.
- Full Text: false
- Date Issued: 2016
- Authors: Chithambo, Makaiko L , Pagonis, Vasilis , Ankjærgaard, Christina
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124743 , vital:35658 , https://doi.org/10.1016/j.physb.2015.10.014
- Description: Time-resolved optical stimulation of luminescence has become established as a key method for measurement of optically stimulated luminescence from quartz, feldspar and α-Al2O3:C, all materials of interest in dosimetry. The aim of time-resolved optical stimulation is to separate in time the stimulation and emission of luminescence. The luminescence is stimulated from a sample using a brief light pulse and the emission monitored during stimulation in the presence of scattered stimulating light or after pulsing, over photomultiplier noise only. Although the use of the method in retrospective dosimetry has been somewhat limited, the technique has been successfully applied to study mechanisms in the processes leading up to luminescence emission. The main means for this has been the temperature dependence of the luminescence intensity as well as the luminescence lifetimes determined from time-resolved luminescence spectra. In this paper we review some key developments in theory and applications to quartz including methods of evaluating lifetimes, techniques of evaluating kinetic parameters using both the dependence of luminescence intensity and lifetime on measurement temperature, and of lifetimes on annealing temperature. We then provide an overview of some notable applications such as separation of quartz signals from a quartz–feldspar admixture and the utility of the dynamic throughput, a measure of luminescence measured as a function of the pulse width. The paper concludes with some suggestions of areas where further exploration would advance understanding of dynamics of luminescence in quartz and help address some outstanding problems in its application.
- Full Text: false
- Date Issued: 2016
F-and F+-band radioluminescence and the influence of annealing on its emission spectra in Al2O3: C, Mg:
- Chithambo, Makaiko L, Kalita, Jitumani M, Finch, A A
- Authors: Chithambo, Makaiko L , Kalita, Jitumani M , Finch, A A
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150130 , vital:38942 , https://doi.org/10.1016/j.radmeas.2020.106306
- Description: Radioluminescence spectra of Al2O3:C,Mg monitored at temperatures up to 400 °C is reported. Measurements were made on samples either as received or on ones annealed at 1200 °C. Radioluminescence is observed at 410 nm for the unannealed sample but principally at 330 and 410 nm in the annealed sample with the emission at 330 nm dominant. Both bands are subject to thermal quenching but the change for the F+ band is atypical. Temperature induced effects on these and other bands are discussed, as are complementary measurements of thermoluminescence spectra.
- Full Text:
- Date Issued: 2020
- Authors: Chithambo, Makaiko L , Kalita, Jitumani M , Finch, A A
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150130 , vital:38942 , https://doi.org/10.1016/j.radmeas.2020.106306
- Description: Radioluminescence spectra of Al2O3:C,Mg monitored at temperatures up to 400 °C is reported. Measurements were made on samples either as received or on ones annealed at 1200 °C. Radioluminescence is observed at 410 nm for the unannealed sample but principally at 330 and 410 nm in the annealed sample with the emission at 330 nm dominant. Both bands are subject to thermal quenching but the change for the F+ band is atypical. Temperature induced effects on these and other bands are discussed, as are complementary measurements of thermoluminescence spectra.
- Full Text:
- Date Issued: 2020
Thermoluminescence of the main peak in SrAl2O4: Eu2+, Dy3+: spectral and kinetics features of secondary emission detected in the ultra-violet region
- Authors: Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124197 , vital:35575 , https://doi.org/10.1016/j.radmeas.2016.12.001
- Description: We report the thermoluminescence of SrAl2O4:Eu2+,Dy3+ measured in the ultra-violet region of the spectrum between 300 and 400 nm. Complementary measurements of X-ray excited optical luminescence confirm emission bands of stimulated luminescence in this region. As a further test, optically stimulated luminescence was also measured in this region. The glow curve measured at 1 °C s−1 following irradiation to various doses appears simple and single but is in reality a collection of several components. This was shown by results from the Tm-Tstop method on both ends of the peak, application of thermal cleaning beyond the peak maximum as well as the dependence of the peak on fading. The latter shows that new peaks appear as preceding ones fade. Kinetic analysis of some of the main peaks was carried out giving an activation energy of 0.6 eV. The implication of the results on measurement of phosphorescence, interpretation of dose response and fading is discussed.
- Full Text: false
- Date Issued: 2017
- Authors: Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124197 , vital:35575 , https://doi.org/10.1016/j.radmeas.2016.12.001
- Description: We report the thermoluminescence of SrAl2O4:Eu2+,Dy3+ measured in the ultra-violet region of the spectrum between 300 and 400 nm. Complementary measurements of X-ray excited optical luminescence confirm emission bands of stimulated luminescence in this region. As a further test, optically stimulated luminescence was also measured in this region. The glow curve measured at 1 °C s−1 following irradiation to various doses appears simple and single but is in reality a collection of several components. This was shown by results from the Tm-Tstop method on both ends of the peak, application of thermal cleaning beyond the peak maximum as well as the dependence of the peak on fading. The latter shows that new peaks appear as preceding ones fade. Kinetic analysis of some of the main peaks was carried out giving an activation energy of 0.6 eV. The implication of the results on measurement of phosphorescence, interpretation of dose response and fading is discussed.
- Full Text: false
- Date Issued: 2017
Phosphorescence of orthopaedic–grade ultra high molecular weight polyethylene
- Authors: Chithambo, Makaiko L
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125617 , vital:35801 , https://doi.10.1002/pssc.200776802
- Description: Isothermal luminescence decay curves have been measured from orthopaedic–standard ultra high molecular weight polyethylene between 35 and 70 ˚C on the rising edge of the main glow peak at 70 ˚C. Preparatory peak-shape analysis of the temperature-resolved glow peak at 70 ˚C measured at 1 ˚C s–1 gave a geometrical factor close to 0.5 suggestive of second order kinetics for both the isothermal and thermally stimulated luminescence. The results of analysis of the phosphorescence of transformed monotonic-to-peak isothermal decay curves are also second order, as is the conclusion from thermoluminescence glow-curve de-convolution. All methods of analysis give an activation energy of about 0.7 eV.
- Full Text:
- Date Issued: 2008
- Authors: Chithambo, Makaiko L
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125617 , vital:35801 , https://doi.10.1002/pssc.200776802
- Description: Isothermal luminescence decay curves have been measured from orthopaedic–standard ultra high molecular weight polyethylene between 35 and 70 ˚C on the rising edge of the main glow peak at 70 ˚C. Preparatory peak-shape analysis of the temperature-resolved glow peak at 70 ˚C measured at 1 ˚C s–1 gave a geometrical factor close to 0.5 suggestive of second order kinetics for both the isothermal and thermally stimulated luminescence. The results of analysis of the phosphorescence of transformed monotonic-to-peak isothermal decay curves are also second order, as is the conclusion from thermoluminescence glow-curve de-convolution. All methods of analysis give an activation energy of about 0.7 eV.
- Full Text:
- Date Issued: 2008
Time-resolved luminescence: progress in development of theory and analytical methods
- Authors: Chithambo, Makaiko L
- Date: 2019
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/105403 , vital:32509 , https://doi.org/10.1142/9781786345790_0007
- Description: Time-resolved optical stimulation is an important method for measurement of optically stimulated luminescence. The aim of time-resolved optical stimulation is to separate the stimulation and emission of luminescence in time. The luminescence is stimulated from a sample using a short light pulse of constant intensity. The ensuing luminescence can be monitored either during stimulation in the presence of scattered stimulating light, or after the light-pulse. The time-resolved luminescence spectrum produced in this way can be resolved into components, each with a distinct lifetime. The lifetimes are linked to physical processes of luminescence. Time-resolved optical stimulation has thus been used to study dynamics of luminescence in various materials, particularly ones of interest in dosimetry such as quartz, feldspar, α-Al2O3:C and BeO. This chapter will review the theory of time-resolved luminescence, look at the instrumentation involved and discuss advances in analytical methods of time-resolved luminescence spectra.
- Full Text: false
- Date Issued: 2019
- Authors: Chithambo, Makaiko L
- Date: 2019
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/105403 , vital:32509 , https://doi.org/10.1142/9781786345790_0007
- Description: Time-resolved optical stimulation is an important method for measurement of optically stimulated luminescence. The aim of time-resolved optical stimulation is to separate the stimulation and emission of luminescence in time. The luminescence is stimulated from a sample using a short light pulse of constant intensity. The ensuing luminescence can be monitored either during stimulation in the presence of scattered stimulating light, or after the light-pulse. The time-resolved luminescence spectrum produced in this way can be resolved into components, each with a distinct lifetime. The lifetimes are linked to physical processes of luminescence. Time-resolved optical stimulation has thus been used to study dynamics of luminescence in various materials, particularly ones of interest in dosimetry such as quartz, feldspar, α-Al2O3:C and BeO. This chapter will review the theory of time-resolved luminescence, look at the instrumentation involved and discuss advances in analytical methods of time-resolved luminescence spectra.
- Full Text: false
- Date Issued: 2019
Time-resolved luminescence of low sensitivity quartz from crystalline rocks
- Chithambo, Makaiko L, Preusser, F, Ramseyer, K, Ogundare, F O
- Authors: Chithambo, Makaiko L , Preusser, F , Ramseyer, K , Ogundare, F O
- Date: 2007
- Language: English
- Type: text , article
- Identifier: vital:6801 , http://hdl.handle.net/10962/d1004164 , https://doi.org/10.1016/j.radmeas.2006.07.005
- Description: preprint , Time-resolved luminescence spectra of low sensitivity natural quartz from crystalline rocks are presented. The luminescence was pulse-stimulated at width using 470 nm blue light from quartz separated from plutonic, metamorphic, volcanic and hydrothermal samples. Measurements were made at 20 °C. All samples show evidence of a short lifetime component less than long although in several cases too weak in intensity to be evaluated accurately. On the other hand, the value of the principal lifetime component varies considerably being about in metamorphic quartz, in plutonic quartz, and in one example of hydrothermal quartz. The results illustrate a new feature of luminescence from quartz for which lifetimes less than or greater than have never been reported at room temperature before. It is argued that the thermal provenance of the quartz and so the annealing it will have experienced influences the size of the observed lifetime. In particular, the results are explained in terms of a model consisting of three luminescence centers with the dominant lifetime linked to preferential recombination at one center depending on the thermal history of the sample and hence the hole concentration of the center.
- Full Text:
- Date Issued: 2007
- Authors: Chithambo, Makaiko L , Preusser, F , Ramseyer, K , Ogundare, F O
- Date: 2007
- Language: English
- Type: text , article
- Identifier: vital:6801 , http://hdl.handle.net/10962/d1004164 , https://doi.org/10.1016/j.radmeas.2006.07.005
- Description: preprint , Time-resolved luminescence spectra of low sensitivity natural quartz from crystalline rocks are presented. The luminescence was pulse-stimulated at width using 470 nm blue light from quartz separated from plutonic, metamorphic, volcanic and hydrothermal samples. Measurements were made at 20 °C. All samples show evidence of a short lifetime component less than long although in several cases too weak in intensity to be evaluated accurately. On the other hand, the value of the principal lifetime component varies considerably being about in metamorphic quartz, in plutonic quartz, and in one example of hydrothermal quartz. The results illustrate a new feature of luminescence from quartz for which lifetimes less than or greater than have never been reported at room temperature before. It is argued that the thermal provenance of the quartz and so the annealing it will have experienced influences the size of the observed lifetime. In particular, the results are explained in terms of a model consisting of three luminescence centers with the dominant lifetime linked to preferential recombination at one center depending on the thermal history of the sample and hence the hole concentration of the center.
- Full Text:
- Date Issued: 2007
Concerning secondary thermoluminescence peaks in α-Al_2_O_3_:C
- Authors: Chithambo, Makaiko L
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6793 , http://hdl.handle.net/10962/d1003823
- Description: Thermoluminescence characteristics of two subsidiary glow peaks, one below 100°C and the other above 300°C, have been studied for measurements between 30°C and 500°C in α-Al_2_O_3_:C. The thermoluminescence intensity of the lower temperature peak decreased with storage with a half-life of about 150 s. In contrast, the intensity of the higher temperature peak increased with storage towards some maximum. The peak-temperature of each of the secondary glow peaks was essentially constant with dose, whereas that of the main peak decreased with irradiation. The dose response for the three peaks was similar except for sublinear growth in the higher temperature peak at low dose values. These effects are discussed in terms of changes in the concentration of F+ luminescence precursors brought about by competitive electron retrapping at deep electron-traps or hole-traps. This work refines the physics and application of α-Al_2_O_3_:C luminescence in radiation dosimetry.
- Full Text:
- Date Issued: 2004
- Authors: Chithambo, Makaiko L
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6793 , http://hdl.handle.net/10962/d1003823
- Description: Thermoluminescence characteristics of two subsidiary glow peaks, one below 100°C and the other above 300°C, have been studied for measurements between 30°C and 500°C in α-Al_2_O_3_:C. The thermoluminescence intensity of the lower temperature peak decreased with storage with a half-life of about 150 s. In contrast, the intensity of the higher temperature peak increased with storage towards some maximum. The peak-temperature of each of the secondary glow peaks was essentially constant with dose, whereas that of the main peak decreased with irradiation. The dose response for the three peaks was similar except for sublinear growth in the higher temperature peak at low dose values. These effects are discussed in terms of changes in the concentration of F+ luminescence precursors brought about by competitive electron retrapping at deep electron-traps or hole-traps. This work refines the physics and application of α-Al_2_O_3_:C luminescence in radiation dosimetry.
- Full Text:
- Date Issued: 2004
On the correlation between annealing and variabilities in pulsed-luminescence from quartz
- Authors: Chithambo, Makaiko L
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6797 , http://hdl.handle.net/10962/d1003923
- Description: Properties of luminescence lifetimes in quartz related to annealing between 500 and 900ºC have been investigated. The luminescence was pulse-stimulated at 470 nm from sets of granular quartz annealed at 500, 600, 700, 800, and 900ºC. The lifetimes decrease with annealing temperature from about 42 to 33 µѕ when the annealing temperature is increased from 500 to 900ºC. Luminescence lifetimes are most sensitive to duration of annealing at 600ºC, decreasing from 40.2 ± 0.7 µѕ by as much as 7 µѕ when the duration of annealing is changed from 10 to 60 min. However, at 800–900ºC lifetimes are essentially independent of annealing temperature at about 33 µѕ. Increasing the exciting beta dose causes an increase in the lifetimes of the stimulated luminescence in the sample annealed at 800ºC but not in those annealed at either 500 or 600ºC. The temperature-resolved distribution of luminescence lifetimes is affected by thermal quenching of luminescence. These features may be accounted for with reference to two principal luminescence centres involved in the luminescence emission process.
- Full Text:
- Date Issued: 2006
- Authors: Chithambo, Makaiko L
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6797 , http://hdl.handle.net/10962/d1003923
- Description: Properties of luminescence lifetimes in quartz related to annealing between 500 and 900ºC have been investigated. The luminescence was pulse-stimulated at 470 nm from sets of granular quartz annealed at 500, 600, 700, 800, and 900ºC. The lifetimes decrease with annealing temperature from about 42 to 33 µѕ when the annealing temperature is increased from 500 to 900ºC. Luminescence lifetimes are most sensitive to duration of annealing at 600ºC, decreasing from 40.2 ± 0.7 µѕ by as much as 7 µѕ when the duration of annealing is changed from 10 to 60 min. However, at 800–900ºC lifetimes are essentially independent of annealing temperature at about 33 µѕ. Increasing the exciting beta dose causes an increase in the lifetimes of the stimulated luminescence in the sample annealed at 800ºC but not in those annealed at either 500 or 600ºC. The temperature-resolved distribution of luminescence lifetimes is affected by thermal quenching of luminescence. These features may be accounted for with reference to two principal luminescence centres involved in the luminescence emission process.
- Full Text:
- Date Issued: 2006
Luminescence lifetime components in quartz: influence of irradiation and annealing
- Chithambo, Makaiko L, Ogundare, F O
- 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.
- Full Text:
- Date Issued: 2009
- 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.
- Full Text:
- Date Issued: 2009
Phototransferred thermoluminescence of synthetic quartz: analysis of illumination-time response curves
- Chithambo, Makaiko L, Niyonzima, P, Kalita, Jitumani M
- Authors: Chithambo, Makaiko L , Niyonzima, P , Kalita, Jitumani M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/111020 , vital:33364 , https://doi.org/10.1016/j.jlumin.2018.02.029
- Description: Phototransferred thermoluminescence (PTTL) induced in synthetic quartz by 470 nm blue light is reported. The glow curve measured at 5 °C/s up to 500 °C after irradiation to 100 Gy shows six peaks at 94, 116, 175, 212, 280 and 348 °C labelled I through VI and another one at 80 °C (labelled A1). PTTL is only observed for peaks A1 and I and is induced at peak A1 as long as peak III has been removed by preheating and at peak I after preheating to deplete peak VI. The inducement of PTTL even when all peaks have been removed points to deep electron traps in the quartz also acting as donors in addition to the putative ones below 500 °C. The PTTL intensity as a function of duration of illumination for A1 goes through a peak and decreases monotonically or to a stable value depending on the preheating temperature. The change of PTTL intensity as a function of illumination time is described using a set of coupled linear differential equations. The number of acceptors and donors in a particular system described in this way is influenced by the preheating temperature.
- Full Text: false
- Date Issued: 2018
- Authors: Chithambo, Makaiko L , Niyonzima, P , Kalita, Jitumani M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/111020 , vital:33364 , https://doi.org/10.1016/j.jlumin.2018.02.029
- Description: Phototransferred thermoluminescence (PTTL) induced in synthetic quartz by 470 nm blue light is reported. The glow curve measured at 5 °C/s up to 500 °C after irradiation to 100 Gy shows six peaks at 94, 116, 175, 212, 280 and 348 °C labelled I through VI and another one at 80 °C (labelled A1). PTTL is only observed for peaks A1 and I and is induced at peak A1 as long as peak III has been removed by preheating and at peak I after preheating to deplete peak VI. The inducement of PTTL even when all peaks have been removed points to deep electron traps in the quartz also acting as donors in addition to the putative ones below 500 °C. The PTTL intensity as a function of duration of illumination for A1 goes through a peak and decreases monotonically or to a stable value depending on the preheating temperature. The change of PTTL intensity as a function of illumination time is described using a set of coupled linear differential equations. The number of acceptors and donors in a particular system described in this way is influenced by the preheating temperature.
- Full Text: false
- Date Issued: 2018
Orthopaedic grade ultra–high molecular weight polyethylene: some features of the main thermoluminescence glow curve
- Authors: Chithambo, Makaiko L
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125499 , vital:35789 , https://doi.10.1093/rpd/nci661
- Description: Thermoluminescence (TL) characteristics of orthopaedic–grade ultra–high molecular weight polyethylene have been investigated between 20 and 200_C. The TL at 1_C s_1 consists of two glow curves, a weaker intensity peak at 115_C and the main peak at 70_C, studied in this work. TL intensity increases with beta irradiation but with a dose–response influenced by heating rate. On the other hand, the peak maximum is affected by both irradiation and repeated use of a sample. The glow curve shifts to higher temperatures with increase in heating rate but only slightly so with change in beta irradiation dose, properties suggestive of first-order kinetics. Kinetic analysis for activation energy and order of kinetics, based on the discrete trap model, produce somewhat conflicting results. Whereas qualitative analysis of peak symmetry show that first-order kinetics apply, geometrical analysis of the peak shape suggests that the order of kinetics might be other than first-order. Values of activation energy evaluated using the initial rise method were found to be dose dependent and for a given beta dose are in agreement with calculations from peak shape and initial rise methods but less so with results from variable heating rate method.
- Full Text:
- Date Issued: 2006
- Authors: Chithambo, Makaiko L
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125499 , vital:35789 , https://doi.10.1093/rpd/nci661
- Description: Thermoluminescence (TL) characteristics of orthopaedic–grade ultra–high molecular weight polyethylene have been investigated between 20 and 200_C. The TL at 1_C s_1 consists of two glow curves, a weaker intensity peak at 115_C and the main peak at 70_C, studied in this work. TL intensity increases with beta irradiation but with a dose–response influenced by heating rate. On the other hand, the peak maximum is affected by both irradiation and repeated use of a sample. The glow curve shifts to higher temperatures with increase in heating rate but only slightly so with change in beta irradiation dose, properties suggestive of first-order kinetics. Kinetic analysis for activation energy and order of kinetics, based on the discrete trap model, produce somewhat conflicting results. Whereas qualitative analysis of peak symmetry show that first-order kinetics apply, geometrical analysis of the peak shape suggests that the order of kinetics might be other than first-order. Values of activation energy evaluated using the initial rise method were found to be dose dependent and for a given beta dose are in agreement with calculations from peak shape and initial rise methods but less so with results from variable heating rate method.
- Full Text:
- Date Issued: 2006
Optically stimulated luminescence of ultra-high molecular weight polyethylene: a study of dosimetric features
- Chithambo, Makaiko L, Kalita, Jitumani M
- Authors: Chithambo, Makaiko L , Kalita, Jitumani M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/110035 , vital:33217 , https://doi.org/10.1016/j.radmeas.2018.06.006
- Description: We report the dosimetric features of ultra-high molecular weight polyethylene (UHMWPE) using luminescence optically stimulated using 470 nm blue light. Samples irradiated to between 1 and 1000 Gy produces luminescence that increases with irradiation dose to produce a linear dose response between 1 and 1000 Gy. The sample was determined not to be affected by pre-dose in tests using a pre-dose of 4000 Gy. This characteristic precludes the need for elaborate background erasing routines typical of dosimetry experiments. The signal has good reproducibility. We used this property to test recovery of ‘unknown’ doses with encouraging results. It was observed that luminescence can also be stimulated using 870 nm infrared light. The dose response, fading, pre-dose effect and the ability to optically stimulate luminescence from the polymer is discussed in terms of curing involving free-radicals.
- Full Text: false
- Date Issued: 2018
- Authors: Chithambo, Makaiko L , Kalita, Jitumani M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/110035 , vital:33217 , https://doi.org/10.1016/j.radmeas.2018.06.006
- Description: We report the dosimetric features of ultra-high molecular weight polyethylene (UHMWPE) using luminescence optically stimulated using 470 nm blue light. Samples irradiated to between 1 and 1000 Gy produces luminescence that increases with irradiation dose to produce a linear dose response between 1 and 1000 Gy. The sample was determined not to be affected by pre-dose in tests using a pre-dose of 4000 Gy. This characteristic precludes the need for elaborate background erasing routines typical of dosimetry experiments. The signal has good reproducibility. We used this property to test recovery of ‘unknown’ doses with encouraging results. It was observed that luminescence can also be stimulated using 870 nm infrared light. The dose response, fading, pre-dose effect and the ability to optically stimulate luminescence from the polymer is discussed in terms of curing involving free-radicals.
- Full Text: false
- Date Issued: 2018
Phototransferred thermoluminescence of α-Al2O3: C: experimental results and empirical models
- Chithambo, Makaiko L, Seneza, Cleophace, Kalita, Jitumani M
- Authors: Chithambo, Makaiko L , Seneza, Cleophace , Kalita, Jitumani M
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115681 , vital:34215 , https://doi.org/10.1016/j.radmeas.2017.08.009
- Description: The thermoluminescence glow curve of α-Al2O3:C consists of a prominent apparently-single peak and a number of weaker intensity secondary peaks. Phototransferred thermoluminescence (PTTL) from secondary glow peaks in α-Al2O3:C is reported. For completeness and to aid discussion, complementary results for the main peak are included. The problem studied is one of phototransferred thermoluminescence for a system of multiple acceptors and multiple donors. A TL glow curve recorded at 5 °C/s following irradiation to 0.5 Gy shows the main peak (labelled II) at 240 °C and two secondary peaks at 86 °C (peak I) and 360 °C (peak III). Peak I is reproduced under phototransfer after any preheating between 100 and 500 °C. Peak II is also reproduced as a PTTL peak after preheating to any temperature up to 800 °C. For the latter, the duration of preheating matters because if the sample is preheated at 800 °C for say, 6 min, PTTL is obtained but not when this is extended to say, 15 min. No PTTL was observed from peak III at all. A study of the time dependence of the PTTL intensity from peak III, following preheating that removes peaks I and II, shows that its electron trap acts as an acceptor when the duration of illumination to stimulate electrons from deep traps is brief but that when the illumination time is extended, the electron trap for peak III loses some of its trapped electrons to the shallower traps thus acting as a donor trap.
- Full Text: false
- Date Issued: 2017
- Authors: Chithambo, Makaiko L , Seneza, Cleophace , Kalita, Jitumani M
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115681 , vital:34215 , https://doi.org/10.1016/j.radmeas.2017.08.009
- Description: The thermoluminescence glow curve of α-Al2O3:C consists of a prominent apparently-single peak and a number of weaker intensity secondary peaks. Phototransferred thermoluminescence (PTTL) from secondary glow peaks in α-Al2O3:C is reported. For completeness and to aid discussion, complementary results for the main peak are included. The problem studied is one of phototransferred thermoluminescence for a system of multiple acceptors and multiple donors. A TL glow curve recorded at 5 °C/s following irradiation to 0.5 Gy shows the main peak (labelled II) at 240 °C and two secondary peaks at 86 °C (peak I) and 360 °C (peak III). Peak I is reproduced under phototransfer after any preheating between 100 and 500 °C. Peak II is also reproduced as a PTTL peak after preheating to any temperature up to 800 °C. For the latter, the duration of preheating matters because if the sample is preheated at 800 °C for say, 6 min, PTTL is obtained but not when this is extended to say, 15 min. No PTTL was observed from peak III at all. A study of the time dependence of the PTTL intensity from peak III, following preheating that removes peaks I and II, shows that its electron trap acts as an acceptor when the duration of illumination to stimulate electrons from deep traps is brief but that when the illumination time is extended, the electron trap for peak III loses some of its trapped electrons to the shallower traps thus acting as a donor trap.
- Full Text: false
- Date Issued: 2017
Radioluminescence of annealed synthetic quartz
- Chithambo, Makaiko L, Niyonzima, P
- Authors: Chithambo, Makaiko L , Niyonzima, P
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115504 , vital:34150 , https://doi.org/10.1016/j.radmeas.2017.02.005
- Description: The radioluminescence of synthetic quartz annealed at various temperatures up to 1000 °C is reported. The amplitude of the emission bands increases with annealing temperature. In addition, when samples are annealed at temperatures exceeding 700 °C, the intensity of the radioluminescence increases with duration of annealing. The corresponding emission spectra show seven emission bands at 2.04, 2.54, 2.77, 3.04, 3.40, 3.75 and 3.91 eV. The change in dominant emission band with annealing is consistent with annealing-induced variations in lifetimes determined previously from time-resolved optically stimulated luminescence spectra in the same samples.
- Full Text: false
- Date Issued: 2017
- Authors: Chithambo, Makaiko L , Niyonzima, P
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115504 , vital:34150 , https://doi.org/10.1016/j.radmeas.2017.02.005
- Description: The radioluminescence of synthetic quartz annealed at various temperatures up to 1000 °C is reported. The amplitude of the emission bands increases with annealing temperature. In addition, when samples are annealed at temperatures exceeding 700 °C, the intensity of the radioluminescence increases with duration of annealing. The corresponding emission spectra show seven emission bands at 2.04, 2.54, 2.77, 3.04, 3.40, 3.75 and 3.91 eV. The change in dominant emission band with annealing is consistent with annealing-induced variations in lifetimes determined previously from time-resolved optically stimulated luminescence spectra in the same samples.
- Full Text: false
- Date Issued: 2017
Thermoluminescence of annealed synthetic quartz: the influence of annealing on kinetic parameters and thermal quenching
- Dawam, Robert R, Chithambo, Makaiko L
- Authors: Dawam, Robert R , Chithambo, Makaiko L
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/110050 , vital:33218 , https://doi.org/10.1016/j.radmeas.2018.06.004
- Description: The thermoluminescence of synthetic quartz annealed at various temperatures up to 900 °C is reported. Glow curves measured at 1 oCs−1 following beta irradiation to 40 Gy from a sample annealed at 500 °C and from an unannealed one consist of a prominent peak at 70 °C and secondary peaks at 110, 180 and 310 °C. In comparison, the glow peak from the sample annealed at 900 °C consists of three peaks but with the main peak at 86 °C and other lower intensity peaks at 170 and 310 °C. Kinetic analysis was carried out on the main peak only in each case. The order of kinetics of this peak was determined to be first order using various methods. The activation energy was evaluated as an average of 0.90±0.02eV for the unannealed sample and the one annealed at 500 °C. However, when the synthetic quartz is annealed at 900 °C, the activation energy decreases to 0.65±0.02eV. The main point of interest however concerns thermal quenching. It was noted that for the sample annealed at 500 °C as well as the unannealed one, the maximum intensity of the main peak decreases with heating rate. This phenomenon is associated with thermal quenching. When the same experiment is carried out using quartz annealed at 900 °C and irradiated to the same dose, namely 40 Gy, the intensity increases with heating rate. This would imply that this sample is not affected by thermal quenching. Using the notion that the radiative and non-radiative recombination routes are competitive, we repeated the experiment using a low dose of 3 Gy. In this case, the intensity decreased with heating rate showing that the process can be tuned. The activation energy for thermal quenching for the samples annealed at 900 °C, 500 °C and unnannealed one was found as 0.65±0.02eV, 0.82±0.02eV and 0.95±0.06eV. Evidently, annealing affects recombination processes in synthetic quartz.
- Full Text: false
- Date Issued: 2018
- Authors: Dawam, Robert R , Chithambo, Makaiko L
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/110050 , vital:33218 , https://doi.org/10.1016/j.radmeas.2018.06.004
- Description: The thermoluminescence of synthetic quartz annealed at various temperatures up to 900 °C is reported. Glow curves measured at 1 oCs−1 following beta irradiation to 40 Gy from a sample annealed at 500 °C and from an unannealed one consist of a prominent peak at 70 °C and secondary peaks at 110, 180 and 310 °C. In comparison, the glow peak from the sample annealed at 900 °C consists of three peaks but with the main peak at 86 °C and other lower intensity peaks at 170 and 310 °C. Kinetic analysis was carried out on the main peak only in each case. The order of kinetics of this peak was determined to be first order using various methods. The activation energy was evaluated as an average of 0.90±0.02eV for the unannealed sample and the one annealed at 500 °C. However, when the synthetic quartz is annealed at 900 °C, the activation energy decreases to 0.65±0.02eV. The main point of interest however concerns thermal quenching. It was noted that for the sample annealed at 500 °C as well as the unannealed one, the maximum intensity of the main peak decreases with heating rate. This phenomenon is associated with thermal quenching. When the same experiment is carried out using quartz annealed at 900 °C and irradiated to the same dose, namely 40 Gy, the intensity increases with heating rate. This would imply that this sample is not affected by thermal quenching. Using the notion that the radiative and non-radiative recombination routes are competitive, we repeated the experiment using a low dose of 3 Gy. In this case, the intensity decreased with heating rate showing that the process can be tuned. The activation energy for thermal quenching for the samples annealed at 900 °C, 500 °C and unnannealed one was found as 0.65±0.02eV, 0.82±0.02eV and 0.95±0.06eV. Evidently, annealing affects recombination processes in synthetic quartz.
- Full Text: false
- Date Issued: 2018
Influence of annealing on thermoluminescence of natural quartz: kinetic analysis and experimental study of apparent inverse thermal quenching
- Folley, Damilola E, Chithambo, Makaiko L
- Authors: Folley, Damilola E , Chithambo, Makaiko L
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/109996 , vital:33212 , https://doi.org/10.1016/j.radmeas.2018.04.010
- Description: The influence of annealing on the main thermoluminescence glow-peak of natural quartz is reported. For comparison, results from un-annealed quartz are included. The glow-curve measured at 1 °Cs−1 after beta irradiation to 50 Gy revealed six peaks each for quartz annealed at 800 °C for 1 h and the un-annealed sample. The main peak in both quartzes was observed at 72 °C. This report focusses on kinetic analysis of the main peak. The analysis was carried out using various methods consisting of the initial rise, whole glow-peak, peak shape, variable heating rate and phosphorescence-based methods. The activation energy obtained using the various methods ranges between and for the annealed sample and between and for the un-annealed sample. The result suggests that annealing has little effect on the activation energy. The luminescence intensity decreased with heating rate in the un-annealed sample in a manner suggestive of thermal quenching. In contrast, the dependence of intensity on heating rate in the annealed sample is influenced by the dose the sample is irradiated to. Whereas thermal quenching was noted for a dose of 50 Gy in the un-annealed sample, the annealed sample showed evidence of thermal quenching at a low dose of 3 Gy with the opposite effect when irradiated to 50 Gy. The activation energies of thermal quenching were found as and for the un-annealed and annealed samples respectively. We ascribe the apparent dependence of thermal quenching on dose in the annealed sample to competition between radiative and non-radiative transitions at the recombination centre.
- Full Text: false
- Date Issued: 2018
- Authors: Folley, Damilola E , Chithambo, Makaiko L
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/109996 , vital:33212 , https://doi.org/10.1016/j.radmeas.2018.04.010
- Description: The influence of annealing on the main thermoluminescence glow-peak of natural quartz is reported. For comparison, results from un-annealed quartz are included. The glow-curve measured at 1 °Cs−1 after beta irradiation to 50 Gy revealed six peaks each for quartz annealed at 800 °C for 1 h and the un-annealed sample. The main peak in both quartzes was observed at 72 °C. This report focusses on kinetic analysis of the main peak. The analysis was carried out using various methods consisting of the initial rise, whole glow-peak, peak shape, variable heating rate and phosphorescence-based methods. The activation energy obtained using the various methods ranges between and for the annealed sample and between and for the un-annealed sample. The result suggests that annealing has little effect on the activation energy. The luminescence intensity decreased with heating rate in the un-annealed sample in a manner suggestive of thermal quenching. In contrast, the dependence of intensity on heating rate in the annealed sample is influenced by the dose the sample is irradiated to. Whereas thermal quenching was noted for a dose of 50 Gy in the un-annealed sample, the annealed sample showed evidence of thermal quenching at a low dose of 3 Gy with the opposite effect when irradiated to 50 Gy. The activation energies of thermal quenching were found as and for the un-annealed and annealed samples respectively. We ascribe the apparent dependence of thermal quenching on dose in the annealed sample to competition between radiative and non-radiative transitions at the recombination centre.
- Full Text: false
- Date Issued: 2018