Showing papers by "Lester Andrews published in 1973"

Matrix reactions of alkali metal atoms with ozone: Infrared spectra of the alkali metal ozonide molecules

Abstract: The 15°K deposition of alkali metal atoms and ozone molecules at high dilution in argon produced very intense bands near 800 cm−1 and weak bands near 600 cm−1 which showed appropriate oxygen isotopic shifts for assignment to v3 and v2 of the ozonide ion. Energetic considerations and alkali metal effects clearly indicated bonding of the metal cation to the ozonide anion. The use of scrambled isotopic ozones showed that the metal cation was symmetrically bound to the ozonide anion in a C2v structure; the symmetric interionic stretching mode was observed at 281 cm−1 for Cs+O3−. The cesium‐ozone reaction produced argon matrix fundamentals for CsO at 322 cm−1 and Cs2O at 457 cm−1; simultaneous mercury arc photolysis was required to yield the LiO absorption at 752 cm−1 from the lithium‐ozone argon matrix reaction.

Argon matrix Raman spectrum of LiO2. Bonding in the M+O2− molecules and the ionic model

Abstract: The Raman spectrum of LiO2 in argon matrices has been observed using 4880 A excitation. The intraionic (O–O)− mode was observed as a sharp intense band at 1097 cm−1; the symmetric interionic (Li+–O2−) mode was recorded as a weaker broad feature at 694 cm−1. Oxygen‐18 and lithium‐6 substitution confirmed these vibrational assignments. The trend of increasing O2− vibrational frequency with increasing alkali atomic weight in the M+O2− molecules is rationalized using the Rittner ionic model of polarizable ion pairs.

Resonance Raman spectrum and vibrational analysis of the ozonide ion in the argon matrix‐isolated M+O3− species

Abstract: Beams of alkali metal atoms and ozone molecules at high dilution in argon were condensed on a tilted copper wedge at 16°K and were examined by argon and krypton plasma laser excitation. Very intense bands shifted 1010 cm−1 below the exciting lines showed small alkali metal effects and appropriate oxygen‐18 shifts for assignment to the v1 symmetric oxygen‐oxygen mode of the ozonide ion in the M+O3− species. The intense fundamental and a regular progression of overtones out to 4v1 suggest that these spectra are probably due to the resonance Raman effect. Vibrational analysis for six isotopic ozonide species produced the oxygen‐oxygen force constant 4.18 ± 0.11 mdyn/A. The spectroscopic value for the heat of atomization of the ozonide ion calculated from the vibrational constants ω1 = 1028.2 cm−1 and X11 = 4.95 cm−1 for Cs+O3− is 153 kcal/mole, which agrees well with the thermodynamic value.

Matrix reactions of Na, K, Rb, and Cs atoms with N2O: Infrared spectra and geometries of K2O, Rb2O, and Cs2O

Abstract: Reactions of the heavy alkali metal atoms with N2O have been studied using the matrix reaction technique. No sodium oxides were produced; however, the metals K, Rb, and Cs yielded products with infrared absorptions appropriate for assignment to ν3 of the M–O–M high‐temperature molecules. The identification of these molecules is based on oxygen isotopic shifts and on experiments codepositing two different alkali metals. Apex angle calculations indicate that K2O and Rb2O have valence angles in the 160°–180° range and that the Cs2O angle is approximately 130°–140°. This trend is rationalized on the basis of increasing metal‐metal bonding with the more polarizable alkali cation. The KO and CsO fundamentals were observed at 384 and 314 cm−1 in solid nitrogen.

Matrix reactions of lithium atoms with N2O: Infrared spectra of LiO and Li2O

Abstract: Simultaneous matrix deposition of Li atoms and N2O at high dilution in nitrogen has produced new infrared absorptions which show appropriate lithium and oxygen isotopic shifts for vibrational assignment to the high temperature molecules LiO and LiOLi, which were observed in earlier evaporative studies. The identification of LiO and LiOLi was confirmed in mixed isotopic experiments. Isotopic assignments to ν3 of Li2O in nitrogen matrices provide data for calculations of the Li–O–Li bond angle which are consistent with a linear molecule, in agreement with the electric deflection and earlier infrared work on Li2O.