Determination of the age of ivory is important for controlling illegal trafficking and the proper identification of ivory artifacts. Radiocarbon dating is the standard method of determining the age of ivories; however, it requires the destruction of a fragment of the sample. Raman spectroscopy is a nondestructive technique, and therefore can be used on artwork. Moreover, Raman measurements can be done using a portable system, and the data analysis can be performed on the spot once the groundwork is done. Ivories contain two primary components: collagen and bioapatite. Raman spectrum of ivory material is mainly a sum of the vibrational bands of these components. As collagen deteriorates with time, its Raman signal decreases; therefore, the ratio of collagen to bioapatite peaks is smaller in the older samples compared to the younger ones, providing a basis for sample dating. We have compared the results of Raman and radiocarbon measurements applied to a set of elephant ivory fragments and have successfully calibrated the Raman data set using radiocarbon measurements. We found that the Raman collagen to bioapatite peak ratios of the samples can be used as a metric to determine their age, providing a nondestructive technique to assess the age of ivory samples. We have also used singular value decomposition (SVD) to analyze the whole Raman spectra. We have observed clear separation between samples of different ages in the SVD component space. The samples also tended to align along the timeline diagonal in the correct order. The changes in multiple collagen and bioapatite peaks contribute to the differences in Raman spectra of ivory samples of different age.

中文翻译：

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EXPRESS：拉曼光谱可以确定大象的象牙年龄

确定象牙年龄对于控制非法贩运和正确识别象牙制品非常重要。放射性碳测年是确定象牙年龄的标准方法；然而，它需要破坏样品的碎片。拉曼光谱是一种无损技术，因此可用于艺术品。此外，拉曼测量可以使用便携式系统进行，一旦基础工作完成，就可以在现场进行数据分析。象牙含有两种主要成分：胶原蛋白和生物磷灰石。象牙材料的拉曼光谱主要是这些成分的振动带的总和。随着胶原蛋白随时间变质，其拉曼信号减弱；因此，与年轻样品相比，旧样品中胶原蛋白与生物磷灰石峰的比例较小，为样品测年提供依据。我们比较了应用于一组象牙碎片的拉曼和放射性碳测量的结果，并成功地使用放射性碳测量校准了拉曼数据集。我们发现样品的拉曼胶原与生物磷灰石峰值比可用作确定其年龄的指标，提供了一种评估象牙样品年龄的无损技术。我们还使用奇异值分解 (SVD) 来分析整个拉曼光谱。我们已经观察到 SVD 分量空间中不同年龄的样本之间存在明显的分离。样本也倾向于以正确的顺序沿着时间线对角线对齐。多个胶原和生物磷灰石峰的变化导致不同年龄象牙样品的拉曼光谱的差异。我们比较了应用于一组象牙碎片的拉曼和放射性碳测量的结果，并成功地使用放射性碳测量校准了拉曼数据集。我们发现样品的拉曼胶原与生物磷灰石峰值比可用作确定其年龄的指标，提供了一种评估象牙样品年龄的无损技术。我们还使用奇异值分解 (SVD) 来分析整个拉曼光谱。我们已经观察到 SVD 分量空间中不同年龄的样本之间存在明显的分离。样本也倾向于以正确的顺序沿着时间线对角线对齐。多个胶原和生物磷灰石峰的变化导致了不同年龄象牙样品的拉曼光谱的差异。我们比较了应用于一组象牙碎片的拉曼和放射性碳测量的结果，并成功地使用放射性碳测量校准了拉曼数据集。我们发现样品的拉曼胶原与生物磷灰石峰值比可用作确定其年龄的指标，提供了一种评估象牙样品年龄的无损技术。我们还使用奇异值分解 (SVD) 来分析整个拉曼光谱。我们已经观察到 SVD 分量空间中不同年龄的样本之间存在明显的分离。样本也倾向于以正确的顺序沿着时间线对角线对齐。多个胶原和生物磷灰石峰的变化导致不同年龄象牙样品的拉曼光谱的差异。