MARVEL analysis of the rotational–vibrational states of the molecular ions H2D+ and D2H+

Abstract

Critically evaluated rotational–vibrational line positions and energy levels, with associated critically reviewed labels and uncertainties, are reported for two deuterated isotopologues of the H₃⁺ molecular ion: H₂D⁺ and D₂H⁺. The procedure MARVEL, standing for Measured Active Rotational–Vibrational Energy Levels, is used to determine the validated levels and lines and their self-consistent uncertainties based on the experimentally available information. The spectral ranges covered for the isotopologues H₂D⁺ and D₂H⁺ are 5.2–7105.5 and 23.0–6581.1 cm⁻¹, respectively. The MARVEL energy levels of the ortho and para forms of the ions are checked against ones determined from accurate variational nuclear motion computations employing the best available adiabatic ab initio potential energy surfaces of these isotopologues. The number of critically evaluated, validated and recommended experimental (levels, lines) are (109, 185) and (104, 136) for H₂D⁺ and D₂H⁺, respectively. The lists of assigned MARVEL lines and levels and variational levels obtained for H₂D⁺ and D₂H⁺ as part of this study are deposited in the ESI to this paper.