The identification of InOH in the gas phase and determination of its geometric structure

Abstract

The first gas phase observation of the species InOH is reported through the detection of its electronic spectrum in the near ultraviolet region, between 345 and 377 nm. The molecule was generated by the high temperature reaction between H₂O and In metal or between H₂ and In₂O₃, and cooled in a free jet expansion. Two separate electronic transitions have been identified and are tentatively assigned as α¹A’←X̃¹A’ and β¹A‘←X̃¹A’. Values for the vibrational wavenumbers ν₂ (bending vibration) and ν₃ (In–O stretching vibration) have been determined for InOH and InOD in all three electronic states involved. There is evidence that the molecule is quasilinear in its ground electronic state which somewhat complicates the values determined for ν₂ in this state. Rotational structure was easily resolved at the lowest temperature achieved in this work (T_rot≊12 K). Analysis of this structure shows that the molecule is bent in all of the electronic states studied, with a bond angle of about 132° in the X̃ state and about 105° in the α and β states.