Gas-Phase Spectra of MgO Molecules: A Possible Connection from Gas-Phase
  Molecules to Planet Formation
  A more fine-tuned method for probing planet-forming regions, such as
protoplanetary discs, could be rovibrational molecular spectroscopy observation
of particular premineral molecules instead of more common but ultimately less
related volatile organic compounds. Planets are created when grains aggregate,
but how molecules form grains is an ongoing topic of discussion in astrophysics
and planetary science. Using the spectroscopic data of molecules specifically
involved in mineral formation could help to map regions where planet formation
is believed to be occurring in order to examine the interplay between gas and
dust. Four atoms are frequently associated with planetary formation: Fe, Si,
Mg, and O. Magnesium, in particular, has been shown to be in higher relative
abundance in planet-hosting stars. Magnesium oxide crystals comprise the
mineral periclase making it the chemically simplest magnesium-bearing mineral
and a natural choice for analysis. The monomer, dimer, and trimer forms of
(MgO)_n with n = 1 - 3 are analyzed in this work using high-level quantum
chemical computations known to produce accurate results. Strong vibrational
transitions at 12.5 {\mu}m, 15.0 {\mu}m, and 16.5 {\mu}m are indicative of
magnesium oxide monomer, dimer, and trimer making these wavelengths of
particular interest for the observation of protoplanetary discs and even
potentially planet-forming regions around stars. If such transitions are
observed in emission from the accretion discs or absorptions from stellar
spectra, the beginning stages of mineral and, subsequently, rocky body
formation could be indicated.
