Spectra of Rg-water dimers in the region of the D2O ν3 asymmetric stretch (Rg = Ar, Kr, Xe)

Abstract

Spectra of rare gas (Rg) – D2O dimers (Rg = Ar, Kr, Xe) are studied in the region of the D2O ν3 asymmetric stretch (≈2800 cm−1), using a rapid-scan tunable infrared optical parametric oscillator source to probe a pulsed supersonic slit jet expansion. Three bands are observed in each case, labelled according to the D2O rotational transition with which they correlate as: Σ(101) ← Σ(000), Π(101) ← Σ(000), and Σ(000) ← Σ(101). The Ar-D2O bands exhibit various perturbations and line broadening effects. For Kr-D2O, the Π(101) ← Σ(000) and Σ(000) ← Σ(101) bands are simple and relatively unperturbed with almost no resolved Kr isotope structure, while the Σ(101) ← Σ(000) band is highly perturbed and shows large isotope splittings. This latter perturbation is analyzed in detail with good results. For Xe-D2O, the experimental spectra are unfortunately weaker. Analysis of the Π(101) ← Σ(000) and Σ(000) ← Σ(101) bands is again relatively straightforward, but the Σ(101) ← Σ(000) band is even more perturbed than for Kr-D2O and its analysis proves impossible. Line broadening (for Ar-D2O) and vibrational frequency shift effects are described.