Pure rotational spectroscopy of potassium chloride, KCl, up to 930 GHz and isotopically invariant analysis of KCI and NaCl

摘要

The pure rotational spectra of five isotopomers of KCl, i.e. (KCl)-K-39-Cl-35, (KCl)-K-39-Cl-37, (KCl)-K-41-Cl-35, (KCl)-K-41-Cl-37 and (KCl)-K-40-Cl-35 have been recorded with the Cologne terahertz high-resolution spectrometer. A total of 295 new rotational lines have been measured in the frequency region between 170 and 930 GHz. For the isotopomers (KCl)-K-39-Cl-35 and (KCl)-K-39-Cl-37 107 and 82, respectively, rotational transitions were assigned from the vibrational ground state up to the seventh excited vibrational (v :5 7) state while the highest J quantum number was 127 (129). 104 lines were measured for the less abundant isotopomers of (KCl)-K-41-Cl-35 and (KCl)-K-41-Cl-17 with J less than or equal to 128, v less than or equal to 6 and J less than or equal to 131, v less than or equal to 5, respectively. Two lines were assigned to (KCl)-K-40-Cl-35, which has an abundance of 0.01% relative to (KCl)-K-39-Cl-35. The newly measured lines were fitted together with the previously published microwave and millimeter wave transitions to obtain an improved set of molecular parameters for the studied isotopomers.Besides this analysis, the isotopically invariant Dunham parameters U-ij with the Born-Oppenheimer corrections for U-01 have been determined for the potassium as well as sodium chloride. The NaCl experimental data have been taken from our recent submm high-resolution study. where both isotopomers of NaCl were measured. The improved isotopically invariant parameters allow precise frequency predictions for the six KCl and two NaCl isotopomers ((KCl)-K-39-Cl-35, (KCl)-K-39-Cl-37, (KCl)-K-41-Cl-35, (KCl)-K-41-Cl-37, (KCl)-K-40-Cl-35, (KCl)-K-40-Cl-37, (NaCl)-Na-23-Cl-35 and (NaCl)-Na-23-Cl-37) to be made far into the terahertz region. (C) 2004 Elsevier B.V. All rights reserved.