23 July 2008

Still fluorescing after all these years

fluorescein

Fluorescein is one of the most commonly used fluorescent dyes. The absorption maximum of its basic solutions is at about 494 nm, resulting in a yellowish-orange color. But, when viewed at a right angle to the incident light, an intense, green fluorescence is observed with a maximum at 521 nm. The fluorescence results when some of the absorbed radiation is emitted as less energetic photons, hence the higher wavelength of emission compared to that of excitation (the rest of the absorbed energy is given off as heat).

In the picture above, you can see both the green fluorescence and the yellow-orange transmitted light.

During my postdoc years I did quite a bit of fluorescence spectroscopy. Fluorescein and its derivatives were among the often used dyes in our arsenal. So when I was leaving the lab for good in the fall of 1991 for my current desk job, I took a small bottle of fluorescein solution as a memento. It is still green.


3 comments:

Cindy said...

Cool...that reminds me, it's been awhile since I checked the level of coolant in my car....

AYDIN ÖRSTAN said...

Ha Ha Ha...what makes coolant solutions glow green is probably fluorescein, indeed.

Katie said...

Cool momento to have. Unfortunately, there is nothing really that I want to take when I leave my lab. Enyme kinetics just don't have "cool stuff" like that.