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 thermal and photostability, and only little triplet formation. The dye is very stable under physiological pH-values and in buffers up to pH 8.5. However, it slowly degrades at higher pH.

ATTO 647 and its derivatives are supplied as crystalline solids. The dye is very hydrophilic and highly water soluble. After coupling to a substrate the dye moiety is electrically neutral. For details of coupling see our recommended labeling procedure (PDF). The fluorescence is excited most efficiently in the range 615 - 660 nm. A suitable excitation source, for instance, is the 647 nm line of the Krypton-Ion laser or a Diode-Laser emitting at 650 nm.