With the wide range of Alexa Fluor® dyes there is something for every filter and many options for multiplex detection. This series of superior fluorophores:

  • Spans the near-UV, visible and near-IR spectrum (Figure 1, Table 1).
  • Are compatible with all common excitation sources (Table 2) and instruments
  • Can replace standard fluorophores for most applications (Table 3)
  • Produce the brightest and most photostable conjugates, for multiplexing and multicolor detection

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Emission Spectra

Emission Spectra

Figure 1. Emission spectra for Alexa Fluor® dyes.

Table 1. Properties of Alexa Fluor® Dyes

Alexa Fluor® dye Absorption
max. (nm)
max (nm)
Emission color* Extinction
Alexa Fluor® 350346442Blue19,000
Alexa Fluor® 405401421Blue34,000
Alexa Fluor® 430433541Green/Yellow16,000
Alexa Fluor® 488496519Green71,000
Alexa Fluor® 532532553Yellow81,000
Alexa Fluor® 546556573Orange104,000
Alexa Fluor® 555555565Orange150,000
Alexa Fluor® 568578603Orange/Red91,000
Alexa Fluor® 594590617Red73,000
Alexa Fluor® 610612628Red138,000
Alexa Fluor® 633632647Far Red239,000
Alexa Fluor® 635633647Far Red140,000
Alexa Fluor® 647650665Near-IR***239,000
Alexa Fluor® 660663690Near-IR***132,000
Alexa Fluor® 680679702Near-IR***184,000
Alexa Fluor® 700702723Near-IR***192,000
Alexa Fluor® 750749775Near-IR***240,000
Alexa Fluor® 790784814Near-IR***270,000
* Typical emission color seen through the eyepiece of a conventional fluorescence microscope with appropriate filters.
** Extinction coefficient at lmax in cm-1M-1. 
*** Human vision is insensitive to light beyond ~650 nm; it is not possible to view near-IR fluorescent dyes.

Table 2. Common Fluorescence Excitation Sources

Source Principal lines (nm)
Mercury arc lamp366, 405, 436, 546, 578*
Xenon arc lamp250-1000*
Tungsten–halogen lamp350-1000*
Blue diode laser405
Helium–cadmium laser325, 442
Argon ion laser457, 488, 514
Nd:YAG laser532**
Helium–neon laser543, 594, 633
Yellow diode laser561
Krypton ion laser568, 647
Red diode laser635
* Continuous white-light source.
** Frequency-doubled principal line output.

Table 3. Alexa Fluor® Dye Equivalents of Common Dyes

If you are using Try this Alexa Fluor® dye
AMCA, coumarinAlexa Fluor® 350
Cy®2, FITC (fluorescein)Alexa Fluor® 488
Cy®3, TRITC (rhodamine)Alexa Fluor® 555
Rhodamine redAlexa Fluor® 568
Texas Red®Alexa Fluor® 594
C®y5Alexa Fluor® 647
Cy®5.5, IR680Alexa Fluor® 680
Cy®7Alexa Fluor® 750