NIST Special Publication 922, Polycyclic Aromatic Hydrocarbon Structure Index, is presented by the Chemical Science and Technology Laboratory as an aid in the identification of the chemical structures and nomenclature of 660 common (and not so common) polycyclic aromatic hydrocarbons (PAHs). This electronic version of the Structure Index allows you to browse or search to display name(s), chemical structures, Chemical Abstracts Service (CAS) Registry numbers, molecular weights, and molecular descriptors.