Rovibronic energy levels are determined for four low-lying electronic states (X 3 Σ-, A 3Π, a 1 Δ, and c 1 Π) of the imidogen free radical (14 NH) using the MARVEL (Measured Active Rotational-Vibrational Energy Levels) technique. Compilation of transitions from both laboratory measurements and solar spectra, found in 18 publications, yields a dataset of 3002 rovibronic transitions forming elements of a measured spectroscopic network (SN). At the end of the MARVEL procedure, the majority of the transitions form a single, self-consistent SN component of 2954 rovibronic transitions and 1058 energy levels, 542, 403, and 58 for the X 3 Σ-, A 3Π, and c 1 Π electronic states, respectively. The a 1 Δ electronic state is characterized by 55 Λ-doublet levels, counting each level only once. Electronic structure computations show that unusually the CCSD(T) method does not accurately predict the a 1 Δ excitation energy even at the complete basis set limit.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry