PURE WATER VAPOR ABSORPTION IN THE 500 $cm^{-1}$ REGION

Author Institution: Astronomy Research Facility, University of Massachusetts; Astronomy Research Facility, National Environmental Satellite ServiceSpectra of pure water vapor have been measured at four different water vapor pressures ranging from 4 to 17 mmHg in a 30 meter absorption cell--used in a six-pass mode (180 meter equivalent optical path). The spectral region, 500-550 $cm^{-1}$ was covered with resolving power, $\Delta\nu = 0.3$ $cm^{-1}$. Results obtained from the data are compared with those in the literature and with theoretical calculations. The observed continuum near 531 $cm^{-1}$ is presumed to have two components: far-wing absorption, and a proposed dimer contribution. As these factors are both expected to have the same pressure dependence, viz., $\ell$nT $\sim$ $P^{2}$, but an oppositely varying temperature dependence, some lower temperature ($275^{\circ} K$) measurements are also discussed