METAL HYPERFINE-STRUCTURE IN MAGNESIUM-CHLORIDE - THE MILLIMETER-WAVE SPECTRUM OF (MGCL)-MG-25 AND (MGCL)-MG-26

Rotational spectra of the magnesium and chlorine isotopomers of MgCl (X 2SIGMA+) have been measured in the frequency range 260-380 GHz using direct absorption techniques. The species studied ((MgCl)-Mg-25-Cl-35, (MgCl)-Mg-25-Cl-37, (MgCl)-Mg-26-Cl-37, (MgCl)-Mg-26-Cl-37) were created in a dc glow discharge by the reaction of magnesium vapor with CCl4. Several rotational transitions were recorded for each isotopomer, and fine structure, as well as hyperfine splittings due to the Mg-25 nucleus, were observed. Rotational, spin-rotation and hyperfine constants were determined for these radicals. The average value of the Fermi contact term was b(F)(Mg-25) = -317.8 (4.9) MHz, indicating a large electron density at the magnesium nucleus.