CO₂作为一种流体包裹体中常见的组分,对其中碳同位素的定量研究,能够提供很多地质历史时期地质流体源区的地球化学信息,并为地球碳循环的研究奠定基础。传统的质谱测试存在无法进行单个流体包裹体测试的缺点。拉曼光谱因其快速、无损、高精度的特点被广泛应用于地球科学各个研究领域,尤其在单一流体包裹体的研究中更为重要。当前,拉曼光谱在定性研究物质结构和成分方面已经十分成熟,相比之下,拉曼光谱定量研究仍显不足。结合前人的研究和实际的实验,根据对拉曼光谱基本原理的分析,提出激光拉曼光谱定量研究应当基于相对散射强度进行,且利用¹³CO₂和¹²CO₂的拉曼谱峰强度比( \begin{array}{c}{I}_{+}^{13}\end{array} / \begin{array}{c}{I}_{+}^{12}\end{array} )表征流体包裹体中CO₂的碳同位素组成是可行的。而影响该方法应用的是其较低的准确度,解决这一问题的关键在于如何在单次实验中同时获得准确而强度较高的 \begin{array}{c}{I}_{+}^{13}\end{array} 和 \begin{array}{c}{I}_{+}^{12}\end{array} 的值。

Carbon dioxide is a common and important component in fluid inclusions. Because carbon isotopic ratio of CO₂ in fluid inclusion can provide geochemical characteristics of source rocks, many works have been conducted to measure the carbon isotopic ratio (¹³C/¹²C) of CO₂. In general, carbon isotopic composition (¹³C/¹²C) of CO₂ fluid inclusions are measured by mass spectroscopy. However, mass spectroscopy is a destructive analytical technique, and can not be applied to measure single inclusion. Raman spectroscopy is an efficient non-contact and non-destructive method, and has been widely employed in many research fields. In fact, due to the difference of carbon atom mass, the Femi resonance of ¹³CO₂ is lower than that of ¹²CO₂, so they can be identified in Raman spectrum. In principle, the carbon isotopic composition (¹³CO₂/¹²CO₂) in CO₂ is closely related to the Raman intensity ratio between ¹³CO₂ and ¹²CO₂ ( \begin{array}{c}{I}_{+}^{13}\end{array} / \begin{array}{c}{I}_{+}^{12}\end{array} ). Therefore, Raman spectroscopy can theoretically be utilized to measure the carbon isotopic composition (¹³CO₂/¹²CO₂) of CO₂. However, this method is seriously hampered by the poor measurement accuracy and precision. In this study, based on the theoretical analysis, and in combination with previous Raman studies on carbon isotopic composition in CO₂, a preliminary research on Raman quantitative measurement for carbon isotopic composition in CO₂ was carried out.