This paper presents a spectroscopic analysis and solubility study of rosin, copal, and Burmese amber samples to reveal the structural changes that occur during amber formation. The infrared spectra indicate that during the long geological process of amber formation, small resin molecules first crosslinked and slowly oxidized, eventually forming a stable organic polymer mixture. An analysis of Raman peak areas demonstrated that among the tested samples, the degree of polymerization is highest in Burmese amber and lowest in rosin. Ultraviolet-visible spectra indicate the presence of unsaturated bonds (e.g., carbonyl groups) or conjugated systems in Burmese amber, copal, and rosin. The evaluation of amber, rosin, and copal solubility in six solvents (ethanol, acetone, 1,4-dioxane, ethylacetate, N,N-dimethylamide, and dichloromethane) demonstrated that solubility decreases in the following order: rosin > copal > Burmese amber. Together, the results suggest that the structure of Burmese amber includes large organic molecules containing six-membered rings along with CH₂, CH₃, C=O, C=C, C–O, and C–C groups.

中文翻译：

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基于琥珀，钴和松香光谱特征比较的缅甸琥珀石化过程中的结构演变

本文介绍了松香，椰子和缅甸琥珀样品的光谱分析和溶解度研究，以揭示琥珀形成过程中发生的结构变化。红外光谱表明，在琥珀形成的漫长地质过程中，小的树脂分子首先交联并缓慢氧化，最终形成稳定的有机聚合物混合物。拉曼峰面积的分析表明，在测试样品中，聚合度在缅甸琥珀中最高，在松香中最低。紫外线可见光谱表明缅甸琥珀，椰棕和松香中存在不饱和键（例如羰基）或共轭体系。评估琥珀色，松香和椰脂在六种溶剂（乙醇，丙酮，1,4-二恶烷，乙酸乙酯，N，N-二甲基酰胺，和二氯甲烷）表明溶解度按以下顺序降低：松香>椰棕>缅甸琥珀。总之，结果表明缅甸琥珀的结构包括含有六元环的大有机分子以及CH₂，CH ₃，C = O，C = C，C–O和C–C组。