Work

The Elusive Bound OH-Stretching First Overtone of Water Dimer

Year: 2026

Type: article

Abstract: Water dimer is a classical example of an OH···O hydrogen bound complex and plays a critical role in the atmosphere. The bound OH-stretching (OH b ) fundamental transition displays the characteristic wavenumber redshift and intensity enhancement, observed repeatedly under many different experimental conditions. In contrast, the first OH b -stretching overtone is predicted to be several orders of magnitude weaker in intensity. Recent full-dimensional ro-vibrational calculations have revised earlier theoretical predictions, suggesting that the OH b -stretching first overtone may exhibit an intensity comparable to that of other observed OH-stretching transitions at these higher wavenumbers. Using jet expansion cavity ring-down spectroscopy in the predicted spectral region, we successfully observed this previously elusive transition. The observed transition wavenumber, intensity, and band shape show excellent agreement with the new theoretical predictions. The overlap of many closely lying ro-vibrational transitions, even at the cold temperature of the jet, gives rise to a relatively unstructured broad band. We determine the experimental OH b -stretching first overtone vibrational band origin to be 7049 cm –1 and estimate the lifetime to be about 10 ps.

Source: The Journal of Physical Chemistry A

DOI: 10.1021/acs.jpca.5c07868

Authors: Henrik G. Kjaergaard, Emil Vogt, Alexandr S. Bogomolov, Clément Lauzin

Institutions: University of Copenhagen, UCLouvain

Language: English

Topic: Molecular Spectroscopy and Structure

Subfield: Spectroscopy

Field: Chemistry

Domain: Physical Sciences

Open Access status: green

Funders: European Commission, Fonds De La Recherche Scientifique - FNRS, Carlsbergfondet, Novo Nordisk Fonden

Awards: G2681369678, G4307904304, G5792135580