1,8-Diazafluoren-9-one

1,8-Diazafluoren-9-one, also known as DFO, is a chemical that is used to find fingerprints on porous surfaces. It makes fingerprints glow when they are lit by blue-green light.

DFO reacts with amino acids present in the fingerprint to form highly fluorescent derivatives. Excitation with light at ~470 nm results in emission at ~570 nm.