REACTIONS OF PULSED-LASER EVAPORATED ALUMINUM ATOMS WITH OXYGEN - INFRARED-SPECTRA OF THE REACTION-PRODUCTS IN SOLID ARGON

Reactions of pulsed-laser evaporated Al atoms with O2 in a condensing argon stream gave cyclic-AlO2 at 496.3 cm-1 as the major product. In addition sharp new absorptions at 1211.2, 1176.3, and 1129.5 cm-1 are identified on the basis of isotopic shifts and multiplets as linear OAlOAlO, AlOAlO, and OAlO, respectively. The identification of linear OAlOAlO and AlOAlO was confirmed by MP2 calculations of isotopic frequencies. The 1129.5-cm-1 band exhibited a sharp mixed oxygen isotopic triplet and isotopic ratio 1.0261 in agreement with that expected for a linear molecule. A sharp 1092.5-cm-1 absorption is identified as OAlOO on the basis of a mixed oxygen isotopic quartet with O-16(2)/(OO)-O-16-O-18/O-18(2) and O-16(2)/O-18(2) reagent mixtures. The only AlO2 isomers observed were the cyclic and linear forms found by theory to be potential minima. The observation of isotopic shifts and mixed isotopic multiplets is absolutely essential for the identification of new transient species.