Detection of the Hydronium Ion (${\mathrm{H}}_3$${\mathrm{O}}^{+}$) by High-Resolution Infrared Spectroscopy

The first high-resolution measurement of the ${\nu }_3$ vibration (doubly degenerate asymmetric stretch) of the hydronium ion (${\mathrm{H}}_3$${\mathrm{O}}^{+}$) is reported. An analysis of sixty transitions in the symmetric and antisymmetric inversion states yields effective band origins of 3530.165(55) and 3513.840(47) ${\mathrm{cm}}^{-1\mathrm{}}$, respectively.