Leica, AD-680-21, ATTO 680 Carboxy Fluorescent Label 1 mg

Optical properties
λ abs = 681 nm
ε max = 1.25×10 5 M -1 cm -1
λ fl = 698 nm
n fl = 30 %
τ fl = 1.7 ns
CF 260 = ε 260 /ε max = 0.30
CF 280 = ε 280 / ε max = 0.17
ATTO 680 belongs together with ATTO 655 and ATTO 700 to a new generation of fluorescent labels.
Characteristic features of the label are strong absorption, high fluorescence quantum yield, good water solubility, and high thermal and photo-stability. ATTO 680 is a zwitterionic dye. After coupling to a substrate the dye moiety is electrically neutral. ATTO 680 is a strong electron acceptor. Its fluorescence is efficiently quenched by electron donors like guanine, tryptophan, etc.
The fluorescence is excited most efficiently in the range 645 - 695 nm . A suitable excitation source for the dye is the Krypton-Ion laser using the 676 nm line or a diode-laser emitting at 670 nm.