FOURIER TRANSFORM MICROWAVE SPECTROSCOPY OF LiNH2 and NaNH2 (~X1A1): COMPARING QUADRUPOLE HYPERFINE INTERACTIONS

Rotational spectra of LiNH$_{2}$ and NaNH$_{2}$ in their \~{X}$^{1}$A$_{1}$ ground electronic states have been recorded using pulsed-beam Fourier transform spectroscopy in the frequency range 22-58 GHz. These species were synthesized in a DC discharge by the reaction of ammonia and the respective laser-ablated alkali metal, in argon carrier gas. Observed transitions were analyzed with previously-measured millimeter-wave frequencies, improving previous rotational constants and determining the metal electric quadrupole hyperfine parameter, $\chi$$_{aa}$, for both species. We find that $\chi$$_{aa}$ (Li) = 0.494 and $\chi$$_{aa}$ (Na) = -7.688. We also compare our results to DFT calculations. A Townes-Dailey analysis of the quadrupole constants suggest that the bonding of the –NH$_{2}$ ligand to lithium and sodium is comparable