1 RHQ Rhodamine 6g 1.000 2 RHB N-[9-(2-carboxyphenyl)-6-(diethylamino)-3h-xanthen-3-ylidene]-N-ethylethanaminium 0.737 3 A1EI4 [9-(2-carboxyphenyl)-6-(dimethylamino)xanthen-3-ylidene]-dimethyl-azanium 0.722