Rhodamine B is used in biology as a staining fluorescent dye, sometimes in combination with auramine O, as the auramine-rhodamine stain to demonstrate acid-fast organisms, notably Mycobacterium.
Rhodamine B is tunable around 610 nm when used as a laser dye.[2] Its luminescence quantum yield is 0.65 in basic ethanol,[3] 0.49 in ethanol,[4]1.0,[5] and 0.68 in 94% ethanol.[6] The fluorescence yield is temperature dependent.[7]