The identification of In2O in the gas phase by high resolution electronic spectroscopy

The molecular species In2O has been identified in the gas phase as a product of the high temperature reaction between water and indium (850 °C) or between indium trioxide (In2O3) and indium (950 °C) by the observation of an electronic transition in the near-ultraviolet. The spectra are simplified by supersonic cooling of the sample in a free jet expansion after it is formed. The vibrational structure shows that the molecule has a very similar geometry in the two states involved while the 18O/16O isotope shift suggests that the molecule is only slightly nonlinear in the excited electronic state. Rotational structure can be resolved at high resolution and shows an intensity alternation; the molecule thus has a symmetric In–O–In arrangement.