Spectral shifts of matrix isolated species as criteria for acid-base interactions with solid Xe

The vibrational spectra of H₂SO₄/H₂O vapors trapped in solid Xe are reported and the spectral shifts are compared to the analogous spectra in argon matrices. In the same matrix layer the ν(OH) stretches of highly acidic species (H₂SO₄ and H ₂SO₄*H₂O) show distinctly larger red shifts as opposed to species of lower acidity or to modes which do not involve directly the O-H bond. A correlation is obtained of the spectral shifts with energies empirically estimated from acidic properties attributed to a variety of molecular species. The hydrogen bonding observed between acidic species and Xe atoms is considered relevant to the formation of xenon hydrides in irradiated matrices. The spectral interpretation is complemented by B3LYP and MP2 calculations of the interaction energies and fundamental modes of vibration.