Spectral features for systematic aluminum replacement in N2H2 and c-N4H4 isomers

Nitrogen’s introduction into the Earth’s atmosphere may stem from interstellar dust particles delivering some form of nitrogen species at the dawn of the planet’s formation. One contributing source of the present nitrogen may be elusive aluminum nitride molecular clusters that are believed to be included within protoplanetary carbonaceous chondritic meteors. The present work utilizes explicitly correlated coupled cluster theory within theoretical spectroscopic techniques to provide rovibrational spectral data for small, cyclic aluminum nitride cluster conformers in the hopes of aiding in searches for such elusive molecules. The most intense transitions for each cluster are the Al$-$H stretches within the 5.2$-5.6\mu m$ range with the most intense transition of 584 km mol⁻¹ exhibited by $c$-Al${}_3$NH${}_4$. Many clusters investigated herein also possess large dipole moments such as 4.45 D from $c-$N${}_4$H${}_4$ in its C${}_{2v}$ conformation. The intense vibrational transitions and large dipole moments for the molecules studied in this work should be instrumental for the rotational, vibrational, or rovibrational detection of aluminum nitride clusters that may shed light on the origin of the nitrogen present within the Earth’s atmosphere and may hold keys for observing other planet-forming regions.