Raman and Infrared Spectra of LiO2 in Oxygen Matrices

Abstract

The Raman spectrum of the LiO₂ molecule has been observed from samples of oxygen codeposited with lithium atoms at 15°K. An intense band at 1093 cm⁻¹ in the Raman spectrum exhibited appropriate oxygen isotopic shifts for assignment to the symmetric oxygen‐oxygen vibrational mode. Experiments using a ¹⁶O₂, ¹⁶O¹⁸O, ¹⁸O₂ sample produced a triplet indicating equivalent oxygen atoms in the LiO₂ molecule. Lithium oxygen vibrations, which were very intense bands in the infrared spectrum, were not detected in the Raman spectrum. The observed Raman intensities strongly support the ionic model for LiO₂ proposed earlier. The experimental apparatus and techniques for laser‐Raman matrix‐isolation spectroscopy are described.