The pure rotational spectrum of CaNH and CaND (X̃A): Additional proof of planarity

The pure rotational spectrum of CaNH in its X̃A ground electronic state has been recorded using millimeter/submillimeter direct absorption methods in the frequency range 320-537 GHz as well as that of CaND. The species were created by Broida-oven techniques. Eleven rotational transitions were observed arising from the v=0 and v=1 states of CaNH, and eight transitions were recorded for the v=1 and v=1 levels. For CaND, eight transitions (v=0) were also measured. For the majority of these transitions, K doublets corresponding to K=0-5 were observed and fine structure splittings were resolved in every component. These spectra were analyzed using an S-reduced Hamiltonian; rotational, centrifugal distortion, and spin-rotation parameters were determined for CaNH, CaND, and the three observed vibrationally excited states. An r structure has also been calculated. The data are consistent with calcium amide being a planar molecule with C symmetry and having predominately ionic bonding, as indicated by previous optical studies. © 2000 American Institute of Physics.