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The rovibrational spectrum of the water molecule is the crown jewel of high-resolution molecular spectroscopy. While its significance in numerous scientific and engineering applications and the challenges behind its interpretation have been well known, the extensive experimental analysis performed for this molecule, from the microwave to the ultraviolet, is admirable. To determine empirical energy levels for H 2 16 O , this study utilizes an improved version of the MARVEL (Measured Active Rotational-Vibrational Energy Levels) scheme, which now takes into account multiplet constraints and first-principles energy-level splittings. This analysis delivers 19027 empirical energy values, with individual uncertainties and confidence intervals, utilizing 309 290 transition wavenumbers collected from 189 (mostly experimental) data sources. Relying on these empirical, as well as some computed, energies and first-principles intensities, an extensive composite line list, named CW2024, has been assembled. The CW2024 dataset is compared to lines in the canonical HITRAN 2020 spectroscopic database, providing guidance for future experimental investigations., (© 2024. The Author(s).)

For the first time the half-width within the complex Robert-Bonamy (CRB) formalism is calculated without making the mean relative thermal velocity approximation. The application is to the nitrogen-broadened half-width of the 500.4-GHz transition (34(2 32)<--34(1 33)) of the ground vibrational state of ozone. For each state of the perturber, the optical cross sections are determined at a number of velocities with the intermolecular potential taken as a sum of electrostatic contributions and Lennard-Jones (6-12) atom-atom components. The dynamics of the collision process are correct to second order in time. Using a nonlinear least-squares fitting method, the optical cross sections are fit to a double power law, which allows the velocity integral for the half-width to be done analytically. The results are compared with the mean relative thermal velocity complex Robert-Bonamy calculations and with measurement. The temperature dependence of the half-width, which is necessary for reduction of remotely sensed data, is determined from both methods and compared with experiment. Copyright 2001 Academic Press.

Pressure-broadened half-widths and pressure-induced line shifts for the two most important bands of water vapor in the 0.7-&mgr;m region are determined using the complex Robert-Bonamy (CRB) formalism. The calculations are made with nitrogen and oxygen as the perturbing gas from which values for air as the perturbing gas are determined. The intermolecular potential is taken as a sum of electrostatic contributions and Lennard-Jones (6-12) atom-atom, and isotropic induction and dispersion components. The dynamics of the collision process are correct to second order in time. The calculated values are compared with published measurements and agreement is observed for both half-widths and line shifts. The temperature dependence of the half-width, which is necessary for reduction of remotely sensed data, is determined. Copyright 2001 Academic Press.