INSTITUDE OF GEOPHYSICS

The use of the blue-UV Infrared stimulated luminescence (IRSL) from feldspars in luminescence dating has generally been unsuccessful due to age underestimation related to anomalous fading. The red emission from feldspar may however provide a non- fading alternative. A series of experiments are reported here which investigate IR stimulated (λ = 833 ± 5 nm) red luminescence emission from potassium feldspar. The aim is to demonstrate the potential of red IRSL as an alternative to the widely used UV-blue emission IRSL approaches. Five key factors are optimised to increase the dose-related red IRSL signal, and to decrease the background signal levels. These include photomultiplier tube (PMT) characteristics, detection filter combinations, laser diode intensity, measurement temperature, and substrate related effects. Preliminary measurements are described that illustrate the considerable potential of red IRSL for dating applications, including low sensitivity changes from volcanic potassi...

Abstract: Abstract: Abstract: Abstract: This paper uses the linear modulation technique to study red IRSL emission of potassium feldspars. Sub-samples were subjected to various pre-treatment and measurement conditions in an attempt to understand the relevant mechanisms of charge transfer. The lin- ear modulation curves fitted most successfully to a sum of three first order components and we present supporting empirical

Luminescence dating is a leading technique for a large spectrum of Quaternary dating applications. Since the development of automated reader systems, handling great amounts of samples has become possible. A large quantity of data is produced in a short time and a detailed check of every single curve is often impractical. Therefore, it is important to be confident in excluding any kind of unwanted signal contributions, such as those from sample carriers. For commonly used types of steel and aluminium (Al) carriers from three laboratories, luminescence characteristics of spurious and radiation-induced signals are presented. TL and OSL emissions of discs show natural (Al) and regenerated thermally stable signals in the UV, UV-blue and red detection range. These signals have characteristic saturation doses of several hundred Gy. Furthermore, we demonstrate light insensitive signal components and phototransferred thermoluminescence (PTTL). Due to high scatter between discs, the proportio...

It has recently been proposed that it may be possible to extend the age range of luminescence dating of loess using the far-red (λ=665-740nm) emission from feldspar, as it is thought not to exhibit anomalous fading. Studies on red luminescence have been hindered due to technical difficulties in suppression of background and other factors. Recently modifications to apparatus (esp. photo-multiplier plus filter combinations) have been reported demonstrating that red IRSL (λ=590-700nm) may be observed from coarse-grained feldspar (Fattahi and Stokes, 2002a). However, this modified system was not able to detect far-red IRSL (λ=665-740nm) from old (>800ka) Chinese loess. In this short note we describe further modifications to the system which have successfully enhanced the far-red IRSL signal, and at the same time reduced background signal levels. As a result, routine measurements of far-red IRSL from loess are possible.

ABSTRACT This article presents the first direct absolute dating method of a Qanat system obtained through optically stimulated luminescence (OSL) dating of grains in spoil heaps, using feldspar single-grain, feldspar multi-grain and quartz multi-grain samples. This novel and highly promising approach to improving our understanding of the chronology of Qanats is more important than the final age results.