(0 0 0) and (0 1 0) States of H218O: analysis of rotational transitions in hot emission spectrum in the 400–850 cm−1 region

✍ Scribed by S.N Mikhailenko; Vl.G Tyuterev; G Mellau

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 304 KB
• Volume: 217
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1016/s0022-2852(02)00018-8

✦ Synopsis

The far-infrared emission spectrum of water vapour have been recorded at temperature 1370 K in the range 400-850 cm À1 at resolutions (FWHM) 0:0055 cm À1 . The measurements have been done in a fused quartz cell with an effective length of hot gas of about 60 cm. Among about 200 lines assigned to the H 2 18 O isotopomer 106 lines have not been reported in previous studies. These newly measured lines correspond to higher values of rotational quantum numbers compared to previous determinations: J max ¼ 18 and K a ðmaxÞ ¼ 17 for the ð0 0 0Þ ð0 0 0Þ band and J max ¼ 15 and K a ðmaxÞ ¼ 11 for the ð0 1 0Þ ð0 1 0Þ band. Estimated accuracy of line position measurements is 0:0005 cm À1 . To our knowledge rotational transitions within an excited bending state have been measured for the first time for H 2 18 O. An extended set of experimental rotational energy levels for (0 0 0) and (0 1 0) vibration states including all previously available data has been determined. A data reduction has been done using the generating function model. The root mean square (RMS) deviation between observed and calculated values is 0:0009 cm À1 for 305 rotational levels of the (0 0 0) state and 0:0007 cm À1 for 198 rotational levels of the (0 1 0) state. A comparison of the observed data with the best available predictions from the molecular electronic potential energy surface [J. Chem. Phys. 106 (1997) 4618] and isotopic effects for rotational levels of (0 0 0) and (0 1 0) states are discussed.