Stokes shift Lucifer Yellow

This fluorophore has excitation maxima at 375 and 400 nm and an emission maximum at 410 nm. The small Stoke s shift may create some difficulty in discrete excitation without contaminating the emission measurement with scattered or overlapping light. The extinction coefficient of the molecule in water is about 27,000M 1cm 1. Cascade Blue and Lucifer Yellow derivatives can be simultaneously excited by light of less than 400 nm, resulting in two-color detection at 410 and 530 nm. 

The spectral characteristics of Lucifer Yellow iodoacetamide produce luminescence at somewhat higher wavelengths than the green luminescence of fluorescein, thus the yellow designation in its name. The excitation maximum for the probe occurs at 426 nm and its emission at 530 nm. The rather large Stoke s shift makes sensitive measurements of emission intensity possible without interference by scattered excitation light. The 2-mercaptoethanol derivative of the fluorophore has an extinction coefficient at pH 7 of about 13,000 M cm-1 at 426nm. 

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