LED based Fourier transform absorption spectroscopy of D216O in 14,800-15,200 cm-1 spectral region

A study of the vibration-rotation absorption spectrum of the D2O molecule in the range 14,800–15,200 cm−1 has been performed. The spectrum was recorded with the spectral resolution of 0.05 cm−1 using a Fourier Transform Spectrometer coupled to a multi-pass White-type cell providing an optical path length of 34.8 m. A light-emitting diode was used as the radiation source giving a high brightness that resulted in an S/N ratio of measurements of about 104. A total of 162 energy levels belonging to four vibrational states were determined. The rovibrational assignment of 309 transitions attributed to D2O was based on the variational calculations. The observed D216O spectrum is, mainly, formed by transitions belonging to the 4ν1 + 2ν2 + ν3, 6ν1 and the 5ν1 + ν3 vibrational bands centered at 14,979.173, 15,049.52, and 15,050.898 cm−1, respectively. It was found that the calculated line positions might deviate from the observed ones up to 0.8 cm−1 indicating the necessity of further optimization of the potential energy surface for the D216O molecule