Leica, AD-647-25, ATTO 647 Carboxy Fluorescent Label 5 mg

Optical properties
λ abs = 647 nm
ε max = 1.2×10 5 M -1 cm -1
λ fl = 667 nm
n fl = 20 %
τ fl = 2.4 ns
CF 260 = ε 260 /ε max = 0.08
CF 280 = ε 280 / ε max = 0.04
ATTO 647 belongs to a new generation of fluorescent labels for the red spectral region. Characteristic features of the label are strong absorption, high fluorescence quantum yield, high photo-stability, and good water solubility. ATTO 647 is a zwitterionic dye with a net electrical charge of zero. The dye is stable at physiological pH-values and in buffers up to pH 8. However, it slowly degrades at higher pH. The dye is very hydrophilic.
The fluorescence is excited most efficiently in the range 615 - 660 nm. A suitable excitation source for ATTO 647 is, next to the He:Ne laser (633nm), the 647 nm line of the Krypton-Ion laser or a diode-laser emitting at 650 nm.