Carboxylic Acids Under Vibrational Scrutiny: Experimental Reference Data to Benchmark Quantum Chemical Calculations

Accurate vibrational reference data on carboxylic acids and their small hydrogen bonded clusters are provided in a multi-spectroscopic study to challenge and test the performance of modern quantum chemical calculations. Furthermore, experimental strategies to characterise particularly relevant structures such as local minima in an environment that can be easily exploited for benchmarking are provided, i.e., without the need of a challenging description of the surroundings on the theory side. The monomers, dimers, trimers, and dimer assemblies of three acids are examined, namely formic, acetic, and pivalic acid. The employed techniques include conventional FTIR and Raman jet spectroscopy, FTIR imaging, and IR depletion spectroscopy in helium nanodroplets