Due to the reversible trans–cis geometric isomerization reaction between trans- and cis-2-methylcyclopropanecarboxylic acid (MCA) in gas-phase, it is impossible to distinguish them by linear infrared spectroscopy experiments. We show that the spectral signatures between trans- and cis-MCA are well resolved in ab initio calculated gas-phase electron-vibration–vibration two-dimensional infrared (EVV 2DIR) spectra. We further analyse the vibration mode pairs that mainly contribute to the intensity of these characteristic cross-peaks. Our work suggests that the EVV 2DIR technique can be used to in situ detect the concentration ratio of each species in the reversible reaction processes.

由于可逆反式-顺式几何异构化反应之间的反式-和顺在气相-2-甲基环丙烷甲酸（MCA），这是不可能通过线性红外光谱实验来区分它们。我们发现，与光谱特征跨-和独联体-mca在很好的解决从头计算的气相电子振动-振动二维红外（EVV 2DIR）光谱。我们进一步分析了主要影响这些特征交叉峰强度的振动模式对。我们的工作表明，EVV 2DIR 技术可用于原位检测可逆反应过程中每种物质的浓度比。