Knowledge Bank

The spectrum of an oxygen-18 enriched water vapor sample has been recorded, between 9 500 and $11500cm-1$, under a resolution of $0.01cm-1$, with the Fourier transform spectrometer built by J. Brault at the Naitonal Solar Observatory (Kitt Peak, Arizona). Its analysis has led to the determination of about 250 accurate rotational energy levels, belonging to the eight interacting vibrational states of $H218O:(041),(220),(121),(022),(300),(201),(102)$, and (003), Moreover, 635 line intensities belonging to the $4\nu 2+\nu 3,2\nu 1+2\nu 2,v1+2v2+v3,2v2+v3,3\nu 1,2v1,2\nu 1+\nu 3,\nu 1+2\nu 3$ and $3\nu 3$ bands have been measured, with an average uncertainty of 6%.