D. T. HALFEN, J. MIN AND L. M. ZIURYS, Department of Chemistry, Department of Astronomy, and Steward Observatory, University of Arizona, Tucson, AZ 85721.
The pure rotational spectrum of the AlC2 (X2A1) radical in the range 4 - 60 GHz has been measured using Fourier transform microwave (FTMW) methods. The species was produced using the Discharge Assisted Laser Ablation Source (DALAS) technique in a supersonic jet expansion of aluminum vapor and CH4, diluted in argon carrier gas. The N = 1 0 and 2 1 transitions have been measured near 22 and 44 GHz, each exhibiting fine structure and hyperfine splittings, arising from the nuclear spin of aluminum, I(27Al) = 5/2. The higher frequency transition was recorded using a newly constructed U-band FTMW system operating at 40 - 60 GHz. The data have been analyzed with a case (b) asymmetric top Hamiltonian, and rotational, fine structure, and hyperfine constants have been determined. Measurements of the 13C isotopologues are currently underway to establish a precise structure for AlC2.