Gas phase infrared spectroscopic observation of the organic acid dimers (CH3(CH2)6COOH)2, (CH3(CH2)7COOH)2, and (CH3(CH2)8COOH)2

This work uses infrared absorption spectroscopy to study the organic acid dimers (CH3(CH2)6COOH)2, (CH3(CH2)7COOH)2, (CH3(CH2)8COOH)2, and their monomers. There is a scarce literature base about these acids and the dimers have not been previously studied in gas phase. Ab initio calculations of vibrational harmonic frequencies are used as a guide for spectroscopic investigations of CO and O–H stretching regions. Correlation between experiment and theory as well as an interesting trend with acid chain length are discussed. Do and De are calculated for all dimers using the B3LYP/6-311++G[3df,3pd] method and are compared to literature values for short chain organic acid dimers.