An experimental water line list at 1950 K in the 6250 -- 6670 \cm\ region

TL;DR

This study records and analyzes an extensive water vapor absorption spectrum at 1950 K, identifying thousands of lines and new energy levels, enhancing spectral databases for high-temperature conditions.

Contribution

It provides a comprehensive experimental water line list at 1950 K, with new energy levels and improved line assignments using combined empirical and theoretical data.

Findings

Identified 2417 absorption lines in the 6250-6670 cm region.

Assigned 2030 lines to 2937 transitions, including 126 new energy levels.

Covered rotational states up to J=27.

Abstract

An absorption spectrum of H$_2$$^{16}$O at 1950 K is recorded in a premixed methane/air flat flame using a cavity-enhanced optical frequency comb-based Fourier transform spectrometer. 2417 absorption lines are identified in the 6250 -- 6670 cm region with an accuracy of about 0.01 cm. Absolute line intensities are retrieved using temperature and concentration values obtained by tunable diode laser absorption spectroscopy. Line assignments are made using a combination of empirically known energy levels and predictions from the new POKAZATEL variational line list. 2030 of the observed lines are assigned to 2937 transitions, once blends are taken into account. 126 new energy levels of H$_2$$^{16}$O are identified. The assigned transitions belong to 136 bands and span rotational states up to $J=27$.