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Preliminary results towards the equivalence of transformed continuous-wave optically stimulated luminescence (CW-OSL) and linearly-modulated LM-OSL) signals in quartz

Kitis G., Polymeris G. S., Kiyak N. G., Pagonis V.

Geochronometria

2011

Vol. 38, no. 3

209-216

The present paper presents a comparative experimental study of two commonly measured Optically Stimulated Luminescence (OSL) signals in quartz. The experimental study measures both the continuous wave OSL (CW-OSL) and the linearly modulated (LM-OSL) signals from the same quartz sample for a range of stimulation temperatures between 180 and 280°C, while the former is transformed to pseudo LM-OSL (ps LM-OSL). A computerized deconvolution curve analysis of the LM-OSL and ps LM-OSL signals was carried out, and the contributions of several OSL components to the initial OSL signal (0.1 s) were shown to be independent of the stimulation temperature used during the measurement. It was also found that the composite OSL (0.1 s) signal consists mainly of the first two OSL components present in the OSL curves. The equivalence of the ps LM-OSL (trans-formed CW-OSL) and of LM-OSL measurements was also examined by an appropriate choice of the experimental stimulation times, and of the stimulation power of the blue LEDs used during the meas-urement.

The characteristics of OSL signal from quartz grains extracted from modern sediments in Japan

Tokuyasu K., Tanaka K., Tsukamoto S., Murray A.

Geochronometria

2010

Vol. 37

13-19

Quartz grains from sediments in Japan are derived from complex mixtures of sources, including volcanic, plutonic, metamorphic and sedimentary rocks. We have measured the OSL signal of quartz grains from modern coastal sediments derived from different source rocks and compared these characteristics with the likely source. Each sample shows a different combination of various OSL components. It is concluded that the source rock affects the characteristics of the OSL components from quartz grains in Japanese sediments. By comparing the LM-OSL signals from volcanic sources with those from various source rocks, it can be deduced that quartz which has a higher fast component ratio is more suitable for dating. We also conclude that volcanic source areas should be avoided.

Component resolved IR bleaching study of the blue LM-OSL signal of various quartz samples

Polymeris G. S., Kiyak N. G., Kitis G.

Geochronometria

2008

Vol. 32

79-85

The present work provides an initial component resolved analysis concerning the effect of infra-red (IR) exposure at elevated temperatures on the blue LM-OSL signal of quartz (stimulated at 470 nm). The study was performed on a total of seven quartz samples, among which five originated from Turkey, one from Greece and one synthetic quartz sample. For these quartz samples, the presence of 6 or even 7 independent LM-OSL components was previously reported, after the application of a computerized decomposition analysis. IR bleaching of each one of these components is studied and compared to the respective signal reduction due to the same thermal treatment solely. It is clearly demonstrated that IR stimulation at temperatures above 50 ° C does not deplete only the fast component in most sedimentary quartz samples studied. Net depletion of fast and medium components resulting from IR exposure is sample-dependent and occurs faster as the stimulation temperature increases. Weak IR bleaching of slow components is also reported in some cases, being more effective for stimulation temperatures up to 100 ° C. No depletion of either the medium or the slow components was detected for stimulation temperatures above 150 ° C. Finally, IR does not stimulate any of the LM-OSL components in the case of the synthetic quartz sample.