Study of H2 16O and H2 18O absorption in the 16,460–17,200 cm−1 range using LED-based Fourier transform spectroscopy

Highlights: • The spectrum of H₂¹⁸O studied between 16,460 and 17,200 cm⁻¹ for the first time. • 287 rotational levels of 19 vibrational states determined for the first time. • Comparison of experimental H₂¹⁶O absorption versus simulation based on the HITRAN2016 list. The spectra of the ₂¹⁶ and ₂¹⁸ vapor have been recorded between 16,460 and 17,200 cm⁻¹ by a Fourier transform spectrometer with spectral resolution of 0.05 cm⁻¹ using high luminance LED light source and 60 cm multipath cell with a path length of 3480 cm. A high signal-to-noise ratio (S/N ≈ 5000) enable us to register the lines with intensities of 1.54 × 10⁻²⁴ to 2.0 × 10⁻²⁷ cm/molecule. More than 1300 lines were recorded in the spectrum of the natural abundance water vapor and over 1800 lines in the spectrum of the vapor enriched by ¹⁸O. 422 rotation-vibration energy levels of the H₂¹⁸O molecule have been assigned to twenty vibrational states. The majority of these energies was attributed to the (241), (321), (340), (420), (401), (500), and (123) states. 43 energy levels were tentatively assigned to the (043), (142), (302), (161), (260), and (062) states. Eleven energy levels were labeled as belonging to the (280), (081), (190), (0 10 0), (1 10 0), (0 11 0), and (0 12 0) states. The recorded spectra were compared with the simulations based on the HITRAN2016 database and variational lists.