Leica, AD-520-21, ATTO 520 Carboxy Fluorescent Label 1 mg

Optical properties
λ abs = 517 nm
ε max = 1.1×10 5 M -1 cm -1
λ fl = 538 nm
n fl = 90 %
τ fl = 3.6 ns
CF 260 = ε 260 /ε max = 0.16
CF 280 = ε 280 / ε max = 0.20
ATTO 520 is a novel fluorescent label related to the well-known dye Rhodamine 6G. Characteristic features of the label are strong absorption, high fluorescence quantum yield, and high thermal and photo-stability. The dye is moderately hydrophilic. Above pH 7.0 the dye exists in an equilibrium with a colorless form (pseudobase). This is a reversible reaction, which does not interfere with the process of coupling to proteins etc. On lowering the pH absorption and fluorescence are restored fully. The fluorescence is excited most efficiently in the range 510 - 535 nm . A suitable source of excitation is an Argon-Ion laser using the 514 nm line.