Electron paramagnetic resonance (EPR) spectroscopy is a well-established method of dating based on trapped charges, applied to various crystalline materials, including carbonates, bones, and teeth. It provides a detailed insight into the structure of radiation defects—paramagnetic centers generated by irradiation, without the need of a painstaking sample preparation, often challenging in other methods. Using EPR we studied the effect of γ radiation on lime mortars and plasters from ancient settlement Hippos in Israel, in order to analyze the process of defect generation. Analysis of the complex spectra revealed the presence of radiation-induced species, including CO2–, NO32– and organic radical. Using an artificial UV source, we generated relatively strong signals of paramagnetic centers, analogous to those created by γ irradiation, reaching their maximum intensity after 5–6 hr of UV exposure. Our results confirm the previous reports that radiation defects can also be generated, instead of bleached, in calcite by UV radiation, which is crucial for identifying the issues related to light exposition, affecting the accuracy of age determinations in trapped-charge dating methods.

中文翻译：

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用 EPR 光谱学研究石灰砂浆和石膏的辐射缺陷

电子顺磁共振 (EPR) 光谱是一种成熟的基于捕获电荷的测年方法，适用于各种晶体材料，包括碳酸盐、骨骼和牙齿。它提供了对辐射缺陷结构的详细洞察——辐射产生的顺磁中心，无需费力的样品制备，这在其他方法中通常具有挑战性。我们使用 EPR 研究了 γ 辐射对以色列古代定居点河马的石灰砂浆和灰泥的影响，以分析缺陷产生的过程。对复杂光谱的分析揭示了辐射诱导物质的存在，包括 CO2–， 不32–和有机自由基。使用人造紫外线源，我们产生了相对强的顺磁中心信号，类似于 γ 辐射产生的信号，在紫外线照射 5-6 小时后达到最大强度。我们的结果证实了之前的报道，即紫外线辐射在方解石中也可以产生辐射缺陷，而不是漂白，这对于识别与光照相关的问题至关重要，这会影响捕获电荷测年方法中年龄确定的准确性。