Knowledge Bank

Sub-millimeter spectra of CaH (X$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$$\Sigma$$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$), MgH (X$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$$\Sigma$$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$), and ZnH (X$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$$\Sigma$$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$) have been measured in the sub-mm$/$THz regime (500$-805$ GHz) using direct{-absorption} methods. All species were produced by the reaction of metal vapor with H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ under DC discharge in a Broida-type oven. Because of efficient molecule production, spectra of $\mathrm{<mrow\; data-mjx-texclass="ORD">26</mrow>}$MgH, $\mathrm{<mrow\; data-mjx-texclass="ORD">66</mrow>}$ZnH, $\mathrm{<mrow\; data-mjx-texclass="ORD">68</mrow>}$ZnH and $\mathrm{<mrow\; data-mjx-texclass="ORD">70</mrow>}$ZnH could be recorded in their natural abundance as well, with high signal-to-noise. Additionally, the N = 0 $\to$ 1 and N = 1 $\to$ 2 transitions of $\mathrm{<mrow\; data-mjx-texclass="ORD">25</mrow>}$MgH and $\mathrm{<mrow\; data-mjx-texclass="ORD">67</mrow>}$ZnH were measured. Fermi contact, dipolar, and quadrupole constants for the $\mathrm{<mrow\; data-mjx-texclass="ORD">25</mrow>}$Mg and $\mathrm{<mrow\; data-mjx-texclass="ORD">67</mrow>}$Zn nuclei have been accurately determined for the first time in the gas phase, and are in good agreement with previous ESR studies. The hyperfine constants suggest a substantial amount of covalent character is present in metal hydrides.