Identification of Trans- and Cis-2-Methylcyclopropanecarboxylic acid using EVV 2DIR spectroscopy: A theoretical study

Due to the reversible trans-cis geometric isomerization reaction between trans- and cis-2-methyl-cyclopropanecarboxylic 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.

Automated summary

The EVV 2DIR technique can effectively distinguish the spectral signatures between trans- and cis-MCA, and further analysis on the contribution of vibration mode pairs to characteristic cross-peaks has been conducted. This provides a method for in situ detection of concentration ratio of each species in reversible reaction processes.