Ground state spectroscopy and photochemistry of HAlOH

Ab initio calculations were carried out in order to study the electronic structure and spectroscopy of cis-HAlOH, trans-HAlOH, H₂AlO, and AlOH₂. The cis structure is more stable than the trans, and both are thermodynamically stable relative to the AlOH + H dissociation limit. A set of spectroscopic constants were generated for the lowest stable isomers to help with their detection in the laboratory and in the interstellar medium. The first excited state absorbs strongly in the visible region (λ = 460 nm), with a predicted transition dipole moment of 2.07 D. The electronic structures of the first excited state were calculated, including the lifetime, adiabatic excitation energy, rotational constants, and frequencies. We have shown that both isomers may be suitable for laser-induced fluorescence detection. Finally, photodissociation of the cis- and trans-HAlOH isomers is a plausible mechanism for the production of AlOH and H.