Terahertz spectroscopy of (NO)-O-18 and isotopic invariant fit of several nitric oxide isotopologs

摘要

A tunable far-infrared laser sideband spectrometer was used to investigate a nitric oxide sample enriched in 180 between 0.99 and 4.75 THz. Regular, electric dipole transitions were recorded between 0.99 and 2.52 THz, while magnetic dipole transitions between the (2)Pi(1/2) and (2)Pi(3/2) spin-ladders were recorded between 3.71 and 4.75 THz. These data were combined with lower frequency data of (NO)-O-18 (unlabeled atoms refer to N-14 and O-16, respectively), with rotational data of NO, (NO)-N-15, (NO)-O-17, and (NO)-N-15-O-18, and with heterodyne infrared data of NO to be subjected to one isotopic invariant fit. Rotational, fine and hyperfine structure parameters were determined along with vibrational, rotational, and Born-Oppenheimer breakdown corrections. The resulting spectroscopic parameters permit prediction of rotational spectra suitable for the identification of various nitric oxide isotopologs especially in the interstellar medium by means of rotational spectroscopy. (C) 2014 Elsevier Inc. All rights reserved.