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.Mechanism of Liquid Scintillation Counting, National Diagnostics, retrieved 24 Sept 2007 POPOP is used in both solid and liquid organic scintillators.
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