Study of HDO absorption in the 11,200-12,400 cm−1 range using LED-based Fourier transform spectroscopy

- Absorption spectrum of HDO between 11,200 and 12,400 cm−1.
- Line positions, intensities and energy levels of HDO are measured.
- Results are compared with the predictions.

A high resolution Fourier transform spectrum of mono-deuterated water vapor was studied between 11,200 and 12,400 cm−1 using a Fourier transform spectrometer with the spectral resolution of 0.05 cm−1, coupled to a multi-pass White-type cell that provided an optical path length of 24 m. A light-emitting diode was used as the radiation source to obtain a measurement signal-to-noise ratio of about 104. The rotational-vibrational assignment of more than 1560 lines was carried out using the VTT variational line list. The parameters of the spectral lines (line centers, intensities and half-widths) were determined by least-squares fitting of the Voigt contour parameters to the experimental data. A total of 584 rotational-vibrational energy levels with maximum rotational quantum numbers of J = 16 and Ka = 9 were determined. For the first time, 64 new energy levels belonging to the nine vibrational states: (032), (112), (301), (141), (410), (221), (330), (061) and (170) were derived from the experiment.