Product Description: AF 647 carboxylic acid is a derivative of the far-infrared dye AF 647. AF 647 is often used as a replacement for Cy5 dye. The maximum excitation wavelength is 648 nm and the maximum emission wavelength is 671 nm. AF 647 carboxylic acid has a carboxylic acid group and can be coupled to biomolecules with amino groups to achieve dye labeling.