15min:

L. N. ZACK, R. L. PULLIAM AND L. M. ZIURYS, Department of Chemistry, Department of Astronomy, Steward Observatory, University of Arizona, Tucson, AZ 85721.

The pure rotational spectra of ZnO in the excited a³ _i electronic state have been measured using direct absorption sub-millimeter techniques. This molecule was synthesized by reacting zinc vapor with N₂O in the presence of a DC discharge. Nine rotational transitions were recorded for the ⁶⁴ZnO, ⁶⁶ZnO, and ⁶⁸ZnO isotopomers in the v=0 state and data for the main isotopomer was measured in the v=1 state. All three spin components were observed for this state, each exhibiting lambda-doubling. The data were fit with a Hund case(a) Hamiltonian and rotational, spin-orbit, spin-spin, and lambda-doubling constants established. A bond length of 1.8436 Å was determined for this excited state, which is about 0.14 Å larger than that of the ground state.