Communication: spectroscopic measurement of the binding energy of a carboxylic acid-water dimer.

Infrared-ultraviolet two color pump-probe spectroscopy is used to measure the binding energy, D(0,) of a carboxylic acid-water dimer where the acid is 9-hydroxy-9-fluorenecarboxylic acid. The acid-water configuration presents a standard structure for the general acid-water interaction where the water bonds to the carboxylic acid group through two intermolecular hydrogen bonds. Photodissociation studies with product vibrational state resolution have enabled an accurate determination of the binding energy for this acid-water system to be D(0) = 2975 ± 30 cm(-1). Quantum chemical calculations are performed to compare with the experimental observations and a recent measurement on the water dimer (D(0) = 1105 ± 10 cm(-1)).