I want to start experimenting with fluorescein. I have a 353 nm UV light source, but am thinking that it might be too short since it looks like peak excitation occurs at 494 nm. So am I correct in assuming that I should buy light sources that emit light at around 494 nm (480 nm for example)?
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$\begingroup$ 494 nm is not ultra-violet.It is in the blue region. So you don't need an UV source to start experimenting with fluorescence. A purple or blue light would do the job. A source at 480 nm is OK. $\endgroup$– MauriceCommented Jan 16, 2021 at 16:56
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$\begingroup$ You have to first look at the excitation spectrum of fluorescein. Where is the peak maximum? You would rather avoid UV due to safety reasons. $\endgroup$– ACRCommented Jan 16, 2021 at 17:06
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1$\begingroup$ Some blue or white LED source could be good enough. $\endgroup$– PoutnikCommented Jan 16, 2021 at 18:01
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$\begingroup$ Your UV source should be fine. If not there are plenty of near-visble UV, low output sources (widely used for revealing the UV security marks in banknotes) and there are even cheap, low power near-visible UV handheld laser pointers or LED sources. $\endgroup$– matt_blackCommented Jan 16, 2021 at 18:02
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1$\begingroup$ BTW, if you use a blue or indigo light source, look through a yellow filter to greatly increase contrast - it blocks blue, but lets yellow-green fluorescence trhough. $\endgroup$– DrMoishe PippikCommented Jan 16, 2021 at 23:38
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