FITC has excitation and emission spectrum peak wavelengths of approximately 495 nm and 519 nm,[5] giving it a green color. Like most fluorochromes, it is prone to photobleaching. Because of the problem with photobleaching, derivatives of fluorescein such as Alexa 488 and DyLight 488 have been tailored for various chemical and biological applications where greater photostability, higher fluorescence intensity, or different attachment groups are needed.