15min:

EMILY D. TENENBAUM, MICHAEL A. FLORY, ROBIN L. PULLIAM AND LUCY M. ZIURYS, Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721.

The radical ZnCl has been studied with high-resolution millimeter-wave spectroscopy in its ^{2 +} ground state. Pure rotational spectra of ⁶⁴Zn³⁵Cl, ⁶⁴Zn³⁷Cl, and ⁶⁶Zn³⁵Cl were measured in the ground and excited vibrational states (v=1,2), and measurements of ⁶⁷Zn³⁵Cl, ⁶⁶Zn³⁷Cl, and ⁶⁸Zn³⁵Cl were recorded in the ground state. Each rotational transition was found to be split into doublets by spin-rotation interactions, and for ⁶⁷Zn³⁵Cl, hyperfine splittings due to the nuclear spin of ⁶⁷Zn (I=5/2) were also observed. Rotational, fine structure, and hyperfine constants have been determined from these data, and equilibrium parameters calculated. The equilibrium bond length of ⁶⁴Zn³⁵Cl was found to be 2.13003(57)Å, in good agreement with recent theoretical predictions. Interpretation of the hyperfine constants indicates that the ZnCl bond is mostly ionic.