Pure rotational spectra of CaOD and MgOD have been recorded in the range 200-390 GHz using millimeter/sub-mm direct absorption spectroscopy. Transitions arising from the (000), (010), (020), and (100) modes have been measured for the 2Σ+ ground electronic states of these free radicals. The data were analyzed successfully using a linear 2Σ+ model for CaOD; for MgOD, only the (000) and (010) states could be fit with this Hamiltonian. Moreover, the (010) data required the addition of a substantial pΠ term to account for contamination of excited 2Π electronic states. For both species, the α2 vibration-rotation term was found to be negative, in contrast to MgOH and CaOH, suggesting a less anharmonic contribution to the bending potential in CaOD and MgOD. These measurements also indicate a shorter O-H bond in MgOH than the other alkaline earth hydroxide radicals, which likely results because this species is quasilinear.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry