FINE AND HYPERFINE ANALYSIS OF RUTHENIUM MONOBORIDE ISOTOPOLOGUES.

Abstract

Using diborane, \chem{B_2H_6}, as a reactant gas and ruthenium as the target metal in the UNB laser ablation molecular jet apparatus, ruthenium monoboride molecules have been detected using laser-induced fluorescence spectroscopy. The [18.4]2.5-X$^{2}$$\Delta$$_{5/2}$ electronic transition of RuB has been observed previously at pulsed-dye laser resolution\footnote{Wang, N., Ng, Y. W. and Cheung, A. S. Chem. Phys. Lett. 547, 21-23 (2012).}. Three vibronic bands were rotationally analyzed and designated as the (1-0), (0-0) and (0-1) bands, but only the Ru$^{11}$B and Ru$^{10}$B isotopologues were resolved. Ruthenium has 7 naturally occurring isotopes ranging from 1.87\% to 31.55\% abundance, giving a total combination of 14 isotopologues for RuB. Using our cw-ring dye laser, the three vibronic bands were recorded at high resolution and 12 of the isotopologues have been rotationally analyzed. Both of the odd isotopes of Ru have a nuclear spin I=5/2 and their respective isotopologues had resolved hyperfine structure which was analyzed to extract the hyperfine parameters. It was determined that the hyperfine interaction arises from the nuclear spin of the $^{101}$Ru and $^{99}$Ru atoms and not from the boron nucleus.