PT Unknown AU Matsushima, F Odashima, H Iwasaki, T Tsunekawa, S Takagi, K TI Frequency measurement of pure rotational transitions of H[sub:2]O from 0.5 to 5 THz SE Conference on precision electromagnetic measurements digest PY 1994 BP 23 EP 24 AB Frequencies of H[sub:2]O pure rotational transitions from 0.5 to 5 THz have been measured with an accuracy of one part in 10[super:9] using a tunable far-infrared spectrometer. Measured frequencies of more than a hundred spectral lines provide an excellent wavelength and frequency calibration standard for the far infrared. ER