2021MNRAS.508.2613W

This work provides the first full set of vibrational and rotational spectral data needed to aid in the detection of AlH₃OH₂, SiH₃OH (silanol), and SiH₃NH₂ (silylamine) in astrophysical or simulated laboratory environments through the use of quantum chemical computations at the CCSD(T)-F12b level of theory employing quartic force fields for the three molecules of interest. Previous work has shown that SiH₃OH and SiH₃NH₂ contain some of the strongest bonds of the most abundant elements in space. AlH₃OH₂ also contains highly abundant atoms and represents an intermediate along the reaction pathway from H₂O and AlH₃ to AlH₂OH. All three of these molecules are also polar with AlH₃OH₂ having the largest dipole of 4.58 D and the other two having dipole moments in the 1.10-1.30 D range, large enough to allow for the detection of these molecules in space through rotational spectroscopy. The molecules also have substantial infrared intensities with many of the frequencies being over 90 km mol^–1 and falling within the currently uncertain 12-17 µm region of observed infrared spectra. The most intense frequency for AlH₃OH₂ is ν₉ that has an intensity of 412 km mol^–1 at 777.0 cm^–1 (12.87 µm). SiH₃OH has an intensity of 183 km mol^–1 at 1007.8 cm^–1 (9.92 µm) for ν₅, and SiH₃NH₂ has an intensity of 215 km mol^–1 at 1000.0 cm^–1 (10.00 µm) for ν₇.