FTIR investigation of the O H Xe interaction in simple carboxylic acids in solid xenon

Abstract

The O–H stretching region of the infrared spectra of a series of carboxylic acids in Xe matrices was investigated as a function of temperature. Upon increasing the temperature, the νO–H band site-components undergo reversible frequency blue-shifts, which are larger for the lowest-frequency components. This unprecedented observation indicates both that different types of O–H···Xe specific interactions occur, depending on different trapping sites, and the prevalence of stronger interactions of this type for molecules trapped in sites corresponding to lower frequency νO–H band site-components. These results are in agreement with previous investigations pointing to an increased stabilization and larger νO–H frequency red-shifts in carboxylic acid/Xe complexes bearing a specific H-bond like O–H···Xe interaction. O–H···Xe interaction energies were obtained theoretically and also estimated from the spectroscopic data. Changes in the interaction energies upon temperature variation were also evaluated.