Molecular astrophysics, developed into a rigorous field of investigation by theoretical astrochemist Alexander Dalgarno beginning in 1967, concerns the study of emission from molecules in space.
High energy radiation, such as ultraviolet light, can break the molecular bonds which hold atoms in molecules.
Most of these locations are relatively cool, and molecular emission is most easily studied via photons emitted when the molecules make transitions between low rotational energy states.
On February 21, 2014, NASA announced a greatly upgraded database for tracking polycyclic aromatic hydrocarbons (PAHs) in the universe.
PAHs seem to have been formed shortly after the Big Bang, are widespread throughout the universe, and are associated with new stars and exoplanets.