Methuselah Green 2™ is a strongly Phosphorescent probe. The Fluorescence band of Methuselah Green 2™ can be excited in the region 300-380 nm, with the Phosphorescence, T₁, band excited 290-350 nm.

Visual comparison of Phos 1™ dissolved at the same concentration in methanol (left cuvette) and in glycerol (right cuvette). The cuvettes are placed on a UV light box and illuminated from below.

Phos Yellow™ dissolved at the same concentrations (~5 µM) in air equilibrated glycerol (left cuvette) and in ethanol (right cuvette). The cuvettes are illuminated from below with UV light.