$H_{2}O$ LINE POSITION MEASUREMENTS AT 1000K

Abstract

A 20 torr $H_{2}O$ sample has been heated to 1000K in a 1.75 m stainless steel absorption cell the spectrum measured with a Michelson interferometer using a maximum optical path difference of 114 cm resulting in an apodized resolution of $0.009 cm^{-1}$. More than 1200 lines were identified in the 1000 to $1400 cm^{-1}$ spectral region. A Loomis-Wood diagram technique proved extremely useful in making the line assignments. After a number of lines had been identified, knowledge of the energy levels derived from these identified lines was used to identity additional lines in a boot-strapping process. When the observed line positions were compared to the line positions on the HITRAN 92 data $base^{1}$, discrepancies of up to $0.8 cm^{-1}$ were found. An important source of self-consistent spectral line data used with the Loomis-Wood diagram technique was obtained from a DND (direct numerical diagonalization) $calculation^{2}$. These line positions were calculated using a 47-Parameter potential surface with up to hextic powers in internal coordinates and generated with a consistent nonlinear least-squares fit. The results of analysis and comparisons with other researchers will be presented at the symposium.