Abstract
The millimetre- and submillimetre-wave spectra of the five common isotopologues of Ge16O in their electronic and vibrational ground state have been recorded in the spectral region 115–732 GHz; for 74Ge16O, the rotational spectrum in the v = 1 state has been detected as well. Exploiting the high precision of the measurements, the Born–Oppenheimer breakdown parameter ΔGe01 could be determined from a Dunham analysis of the spectral data, whereas ΔO01 was obtained from quantum-chemical calculations, because of the lack of high-precision measurements for the Ge18O isotopologues. From the rotational equilibrium constant, the Born–Oppenheimer equilibrium distance of GeO could be determined.
Notes
1. Thermally Pulsating Asymptotic Giant Branch stars.
2. Natural germanium is composed of 70Ge (20.5%), 72Ge (27.4%), 73Ge (7.8%), 74Ge (36.5%) and 76Ge (7.8%).
3. NAh = 3.990 312 7176(28) × 10−10 J s mol−1 with a relative standard uncertainty of 7.0 × 10−10, from the recommended fundamental constants listing CODATA 2010 [Citation4]
4. Value determined from a fit to a power series in of the data from both Ref. [Citation9] and Ref. [Citation10].