Line positions and energy levels of the 18O substitutions from the HDO/D2O spectra between 5600 and 8800 cm−1

Absorption spectra of HDO/D2O mixtures recorded in the 5600-8800 cm−1 region with a total pressure of water from 13 up to 18 hPa and an absorption path length of 600 m have been analyzed in order to obtain new spectroscopic data for HD18O and D218O. In spite of the low natural 18O concentration (about 2×10−3 with respect to the 16O one), about 1100 transitions belonging to HD18O and more than 280 transitions belonging to D218O have been assigned. Most of the D218O transitions belong to the ν1+ν2+ν3 and 2ν1+ν3 bands. Sets of energy levels for seven vibrational states of D218O and four states of HD18O are reported for the first time. The comparison of the experimental data with the calculated values based on Partridge-Schwenke global variational calculations is discussed.