The effect of matrices on the low-temperature IR spectra of a formic acid molecule isolated in inert gas crystals

Abstract

Using the DFT/M06-2X method, we simulated the structure and vibrational spectra of inert gas (Ne, Ar, Kr, Xe) clusters with an isolated formic acid molecule. The impact of the matrix environment on the vibrational spectra of formic acid is established. The values of the matrix shifts of the vibrational frequencies predicted by calculations matched those obtained experimentally. We found that the best agreement between the calculated and experimental shifts occurred for clusters with the smallest deformation energy of the inert gas crystal. At the same time, the ratio of the volume of the molecule embedded in the matrix, and the volume of substituted matrix gas atoms, allowed one to determine only the minimum possible size of the matrix site. The calculated and experimental values of the matrix shifts are in good agreement, indicating the computation method matches the actual experimental conditions. Published under license by AIP Publishing.