# Quenching transitions for the rovibrational transitions of water: Ortho-HO in collision with ortho- and para-H.
> 水分子の回転振動緩和：オルソH₂およびパラH₂との衝突による定量的計算


## Abstract

This study presents a complete quantum mechanical calculation of rovibrational quenching of water molecules from the first bending mode (approximately 1595 cm⁻¹) through collisions with both ortho- and para-H₂. The full coupled-channel formalism was applied within the rigid bender approximation, decoupling rotational and vibrational bases of water. Rotational quantum numbers of H₂ up to 4 (para) and 3 (ortho) were included, and rate coefficients were converged over a kinetic temperature range of 50–500 K using a well-validated full-dimensionality water–hydrogen potential energy surface. The projectile's rotational state was found to exert a dominant influence, producing rate differences spanning orders of magnitude across channels. Overall quenching rate coefficients were approximately 10⁻¹³ cm³ s⁻¹, one to three orders of magnitude below purely rotational quenching rates. These values are intended for astrophysical modeling of warm, dense environments such as protostellar and planet-forming regions accessible to infrared space observatories.

### Mechanism

Using full coupled-channel quantum dynamics with the rigid bender approximation on a validated potential energy surface, the rotational state of H₂ was shown to drive order-of-magnitude variations in rovibrational quenching rate coefficients of water.

## Bibliographic

- **Authors**: Wiesenfeld L
- **Journal**: J Chem Phys
- **Year**: 2022 (2022-11-07)
- **PMID**: [36347679](https://pubmed.ncbi.nlm.nih.gov/36347679/)
- **DOI**: [10.1063/5.0102279](https://doi.org/10.1063/5.0102279)
- **Study type**: other
- **Delivery route**: not specified
- **Effect reported**: not assessed

## Delivery context

The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).

## Safety notes

The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)

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> **Cite as**: H2 Papers — PMID 36347679. https://h2-papers.org/en/papers/36347679
> **Source**: PubMed PMID [36347679](https://pubmed.ncbi.nlm.nih.gov/36347679/)