Frequency measurement of pure rotational transitions of (H2O)-O-17 and (H2O)-O-18 from 0.5 to 5 THz

Frequencies of pure rotational transitions of isotopic species of water, (H 2O)-O-17, and (H2O)-O-18 were measured in the 1-5 THz region with a high-pr ecision far-infrared spectrometer using a tunable radiation source. Measure d frequencies of more than 100 spectral lines for each species provide an e xcellent frequency standard for the far-infrared region. Molecular paramete rs based on a Watson-type Hamiltonian have been obtained to reproduce the o bserved frequencies. (C) 1999 Academic Press.