ExoMol is a recurring research program hosted by Astrojo.
In our first run, we studied OH (Hydroxide), NH (Imidogen) and CN (Cyanide).
In our current run, we are studying 3 isotopolgues of CO2 (Carbon Dioxide).

A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identify atoms and molecules.

Spectral lines are the result of interaction between a quantum system (usually atoms, but sometimes molecules or atomic nuclei) and a single photon.

A table of the intensity of a spectral line and its position is called a Line List.
ExoMol is a database of molecular line lists that can be used for spectral characterisation and simulation, and as input to atmospheric models of exoplanets, brown dwarfs and cool stars, and other models including those for combustion and sunspots.