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> for the fluoreszent effect, it is sufficient that the light has a shorter wavelength than the floreszent color. So any wavelength from normal green into the b

> for the fluoreszent effect, it is sufficient that the light has a shorter wavelength than the floreszent color. So any wavelength from normal green into the blue spectrum should work, no need for UV for that That is not how fluorescence works. You have a fluorescence excitation spectrum offset from the emission spectrum and there is a peak. I don’t have the spectrum for a tennis ball, but it very well could require UV light for any meaningful fluorescence https://www.sciencedirect.com/topics/chemistry/fluorescence-excitation-spectrum https://www.sciencedirect.com/topics/chemistry/fluorescence-...

_ph_ 7y ago
Yes, of course, there is some offset between the absorption range and the emission wavelengths. But there is no requirement for the absorption to be in the UV region. The absorption range is also wide peak. All the fluoreszent colors which "work" with e.g. car headlights have a sufficiently strong effect in the visual range. It is also an easy test for fluorescence to shine e.g. a blue light at something which has a strong orange color. If it still is strong orange, fluorescence obviously is the dominating effect. I don't doubt that UV light shows a strong fluorescent effect, especially as you cannot see the UV light itself, but of course the fluorescent emission it is causing.
- mannykannot 7y ago
  Is there much use of fluorescent colors that work in car headlights? For signs and markings, reflective paints seem to be more effective in showing up under headlights, particularly as the light is directed back towards the source, rather than scattered widely. The article below describes the benefit of fluorescent dyes under weak natural light, as they can use the UV component of natural light to increase the amount of visible light reflected. Downshifting visible light to a longer wavelength, which is what fluorescence excited by visible light would do, would reduce the intensity of the reflected light. https://www.3m.com/3M/en_US/road-safety-us/resources/road-transportation-safety-center-blog/full-story/~/fluorescent-traffic-signs-explained/?storyid=e33bd3e0-36b0-44c0-b416-1b87324b2755 https://www.3m.com/3M/en_US/road-safety-us/resources/road-tr...
mannykannot 7y ago
This discussion could use some examples, and there seem to be some named dyes here that are excited by visible light. On the other hand, the simple fact that it was an issue in the replacement of tennis-court artificial lighting shows that UV excitation is a factor in the fluorescence of the dye used for tennis balls. https://www.thermofisher.com/us/en/home/life-science/cell-analysis/cell-analysis-learning-center/molecular-probes-school-of-fluorescence/fluorescence-basics/fluorescence-fundamentals/light-spectrum-fluorescence.html#excitation https://www.thermofisher.com/us/en/home/life-science/cell-an...

_ph_ 7y ago

Yes, of course, there is some offset between the absorption range and the emission wavelengths. But there is no requirement for the absorption to be in the UV region. The absorption range is also wide peak. All the fluoreszent colors which "work" with e.g. car headlights have a sufficiently strong effect in the visual range. It is also an easy test for fluorescence to shine e.g. a blue light at something which has a strong orange color. If it still is strong orange, fluorescence obviously is the dominating effect. I don't doubt that UV light shows a strong fluorescent effect, especially as you cannot see the UV light itself, but of course the fluorescent emission it is causing.

mannykannot 7y ago
Is there much use of fluorescent colors that work in car headlights? For signs and markings, reflective paints seem to be more effective in showing up under headlights, particularly as the light is directed back towards the source, rather than scattered widely. The article below describes the benefit of fluorescent dyes under weak natural light, as they can use the UV component of natural light to increase the amount of visible light reflected. Downshifting visible light to a longer wavelength, which is what fluorescence excited by visible light would do, would reduce the intensity of the reflected light. https://www.3m.com/3M/en_US/road-safety-us/resources/road-transportation-safety-center-blog/full-story/~/fluorescent-traffic-signs-explained/?storyid=e33bd3e0-36b0-44c0-b416-1b87324b2755 https://www.3m.com/3M/en_US/road-safety-us/resources/road-tr...

mannykannot 7y ago

This discussion could use some examples, and there seem to be some named dyes here that are excited by visible light. On the other hand, the simple fact that it was an issue in the replacement of tennis-court artificial lighting shows that UV excitation is a factor in the fluorescence of the dye used for tennis balls. https://www.thermofisher.com/us/en/home/life-science/cell-analysis/cell-analysis-learning-center/molecular-probes-school-of-fluorescence/fluorescence-basics/fluorescence-fundamentals/light-spectrum-fluorescence.html#excitation https://www.thermofisher.com/us/en/home/life-science/cell-an...