Application of EPR in Studies of Archaeological Samples
Résumé
Electron paramagnetic resonance (EPR), also known as electron spin resonance (ESR), is more and more used in archaeology, and types of materials analyzed or purposes expand each year. Among its applications, dating is one of the most important. Many materials containing quartz or carbonates could be dated, from sediments to tephras including heated lithic artifacts and potteries, but also teeth, speleothems, shells, corals, and even mortars or plasters. The thermal history is also an important information which can be obtained by EPR to understand ancient ways of using fire for cooking or for lithic or ceramic industry. A third application is the determination of the soil or water source, which could help to understand whence original matter used for lithic or ceramic industry came or to describe climatic environment of settlements. Archaeological artifacts can also be studied, leading to the knowledge of ancient pigments and techniques used in glasses, oil paintings, or inks. Ideas of aging status or processes can be obtained for organic materials such as paper, wood, or leather. Finally, other alternative EPR experiments, such as other frequencies than X-band, EPR microscopy, and pulsed EPR, will be described. In several archaeological research domains, EPR has been, only recently, frequently used, and a lot of effort is spent to increase reliability of the results, especially in EPR dating of the earliest or oldest samples, but also in thermal history, and tendencies to try to normalize procedures for better accuracies and easier comparisons are observed.