Low‐Frequency Region of the Infrared Spectrum of Matrix Isolated Vapors from Li2O(s)

The infrared spectrum of matrix‐isolated vapors from solid Li2O has been investigated in the region 60–350 cm−1. At 1640°K, where the polyatomic species Li2O(g) predominates, a single feature is found at 118 cm−1 for 7Li2O(g) and 112 cm−1 for 6Li2O(g). This is assigned to the bending mode v2. At higher temperatures, 1740°K, where the concentration of Li2O2(g) becomes significant, two additional bands are found. On the basis of 6Li–7Li isotopic shifts and relative intensities, it is possible to identify the bands in the region 240–260 cm−1 with the B1u out‐of‐plane mode of Li2O2(g) and those at 231–243 cm−1 to v2 of a new molecular species LiO2(g). A force constant analysis is given. On the basis of the present work it has been concluded that Li2O is most probably linear and LiO2 symmetric and nearly linear.