CM2 chondrites experienced widespread aqueous and short term thermal alteration on their parent bodies. Whilst previous Raman spectroscopic investigations have investigated insoluble organic matter (IOM), they have not taken into account the binary nature of IOM. Studies employing mass spectrometry have indicated that IOM also known as macromolecular organic matter (MOM) is in fact composed of two distinct fractions: labile organic matter (LOM) and refractory organic matter (ROM). The ROM component represents the aromatic rich and heteroatom poor component of IOM/MOM, whilst the LOM fraction represents a more heteroatom and aliphatic rich component. Here we report Raman 2D maps and spectroscopic data for Murchison and Mighei, both before and after chemical degradation, which attacks and liberates LOM. The removal of LOM simulates the effects of aqueous alteration, where ester and ether bonds are broken and is thought to release some components to the soluble organic matter (SOM) fraction, also known as the free organic matter fraction (FOM). Raman spectroscopy can be used to reveal the nature of bonding (sp² and sp³) within carbonaceous materials such as meteoritic organic matter, through evaluation of the D and G band peak centres and FWHM values from the recorded data. The presence of sp³ orbitals indicates that the organic materials contain aliphatic linkages and/or heteroatoms. Statistical analysis of the Raman parameters obtained here indicates that the organic matter originating the Raman response is indistinguishable between the bulk (chemically untreated) and chemically degraded (treated with KOH and HI) samples. Such an observation indicates that the ROM fraction is the major contributor to the Raman response of meteoritic organic matter and thus Raman spectroscopy is unlikely to record any aqueous alteration processes that have affected meteoritic organic matter. Therefore, studies which use Raman to probe the IOM are investigating just one of the components of IOM and not the entire fraction. Studies that aim to investigate the effects of aqueous alteration on meteoritic organic matter should use alternate techniques to Raman spectroscopy. Furthermore, the indistinguishable nature of the Raman response of ROM from Murchison and Mighei suggests these meteorites inherited a ROM component that is chemically similar, reflecting either a common process for the formation of CM2 meteoritic ROM and/or that these meteorites probed the same ROM reservoir.

CM2 球粒陨石在其母体上经历了广泛的水性和短期热变化。虽然之前的拉曼光谱研究已经研究了不溶性有机物 (IOM)，但他们没有考虑到 IOM 的二元性质。使用质谱法的研究表明，IOM 也称为大分子有机物 (MOM)，实际上由两种不同的部分组成：不稳定有机物 (LOM) 和难熔有机物 (ROM)。ROM 组分代表 IOM/MOM 中富含芳香族和缺乏杂原子的组分，而 LOM 部分代表更多杂原子和富含脂肪族的组分。在这里，我们报告了 Murchison 和 Mighei 在化学降解之前和之后的拉曼 2D 地图和光谱数据，化学降解攻击和释放了 LOM。LOM 的去除模拟了水性改变的影响，其中酯键和醚键被破坏，并被认为将一些成分释放到可溶性有机物 (SOM) 部分，也称为游离有机物部分 (FOM)。拉曼光谱可用于揭示键合的性质（sp²和 sp ³）在碳质材料（如陨石有机质）中，通过从记录数据评估 D 和 G 波段峰中心和 FWHM 值。sp ³的存在轨道表明有机材料含有脂肪键和/或杂原子。此处获得的拉曼参数的统计分析表明，产生拉曼响应的有机物质在大块（未经化学处理）和化学降解（用 KOH 和 HI 处理）样品之间无法区分。这样的观察表明 ROM 部分是陨石有机物拉曼响应的主要贡献者，因此拉曼光谱不太可能记录任何影响陨石有机物的水蚀变化过程。因此，使用拉曼探测 IOM 的研究只研究 IOM 的一个组成部分，而不是整个部分。旨在研究含水蚀变对陨石有机物影响的研究应使用拉曼光谱的替代技术。此外，来自 Murchison 和 Mighei 的 ROM 的拉曼响应的不可区分性表明这些陨石继承了化学上相似的 ROM 成分，反映了形成 CM2 陨石 ROM 的共同过程和/或这些陨石探测了相同的 ROM 储层.