Crying Chestnut Branch
A freshly cut chestnut branch (aesculus hippocastanum) is submerged in the darkness into a 1 L beaker that has been filled with water. Under irradiation with violet light (λ = 400 nm) or UV-light (λ = 365 nm) from an LED flashlight, it is possible to see how a blue-whitish glowing substance, esculin, flows from the incision out of the branch and mixes with the water. The luminescent substance (the fluorescence) is invisible under daylight.
Fluorescence of Esculin (The Crying Chestnut Branch)
A short video showing a blue-white glowing substance, esculin, flowing out of the incision into a chestnut branch under irradiation with UV light (λ = 365 nm). The substance spreads within the water.