POPOP Scintillation Grade 1 4-bis5-phenyloxaza-2yl benzene

POPOP or 1,4-bis(5-phenyloxazol-2-yl) benzene is a scintillator. It is used as a wavelength shifter (also called a "secondary scintillator"), which means that it converts shorter wavelength light to longer wavelength light. Its output spectrum peaks at 410 nm, which is violet.