The Effect of Thermal Stimulation on the Far-Red and Orange-Red IRSL Signal of a French K-Rich Feldspar: Preliminary Results

Feldspar suffers from anomalous fading. Previous studies suggest that the level of fading depends on the emission band, and that the fading decreases by increasing the emission wavelengths; therefore, it is interesting to compare blue, orange and far-red IRSL emission characteristics. The purpose of this article is to make an initial consideration of some physical differences between two close emission windows. The effect of the sample temperature on far-red (λ>650 nm) and orangenear-red IRSL (λ=600-650 nm) from an identical feldspar sample is investigated. The difference in signal decay rate and thermal effects is discussed. While there is signal enhancement for far-red IRSL signals between 100-220°C, orange-near-red signals do not change. Some possible mechanisms for producing far-red and orange-near-red IRSL are discussed. This paper shows that orange-near-red IRSL and far-red IRSL thermal activation energies are different. This difference may be the cause of previously observed differences in stability of near and far-red IRSL signals.