With the wide range of Invitrogen™ Molecular Probes™ 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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Alexa Fluor dyes—Emission spectra

Figure 1. Emission spectra for Alexa Fluor dyes.

Table 1. Properties of Alexa Fluor Dyes

Alexa Fluor dye Absorption
max. (nm)
Emission
max (nm)
Emission color* Extinction
coefficient**
Alexa Fluor 350 346 442 Blue 19,000
Alexa Fluor 405 401 421 Blue 34,000
Alexa Fluor 430 433 541 Green/Yellow 16,000
Alexa Fluor 488 496 519 Green 71,000
Alexa Fluor 532 532 553 Yellow 81,000
Alexa Fluor 546 556 573 Orange 104,000
Alexa Fluor 555 555 565 Orange 150,000
Alexa Fluor 568 578 603 Orange/Red 91,000
Alexa Fluor 594 590 617 Red 73,000
Alexa Fluor 610 612 628 Red 138,000
Alexa Fluor 633 632 647 Far Red 239,000
Alexa Fluor 635 633 647 Far Red 140,000
Alexa Fluor 647 650 665 Near-IR*** 239,000
Alexa Fluor 660 663 690 Near-IR*** 132,000
Alexa Fluor 680 679 702 Near-IR*** 184,000
Alexa Fluor 700 702 723 Near-IR*** 192,000
Alexa Fluor 750 749 775 Near-IR*** 240,000
Alexa Fluor 790 784 814 Near-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 lamp 366, 405, 436, 546, 578*
Xenon arc lamp 250-1000*
Tungsten–halogen lamp 350-1000*
Blue diode laser 405
Helium–cadmium laser 325, 442
Argon ion laser 457, 488, 514
Nd:YAG laser 532**
Helium–neon laser 543, 594, 633
Yellow diode laser 561
Krypton ion laser 568, 647
Red diode laser 635
* 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, coumarin Alexa Fluor 350
Cy®2, FITC (fluorescein) Alexa Fluor 488
Cy®3, TRITC (rhodamine) Alexa Fluor 555
Rhodamine red Alexa Fluor 568
Texas Red Alexa Fluor 594
Cy®5 Alexa Fluor 647
Cy®5.5, IR680 Alexa Fluor 680
Cy®7 Alexa Fluor750