An intriguing DIY experiment with chestnut bark

In this experiment, we investigated the fascinating fluorescence of aesculin, a natural ingredient from the bark of the horse chestnut (Aesculus hippocastanum). Aesculin is known for its intense blue-green fluorescence, which is particularly visible under UV light excitation.

Preparation of the solution

To isolate the fluorescent substance, we ground the bark of a chestnut branch and extracted it in ethanol. This process dissolves the aesculin molecules from the bark and produces a clear solution that fluoresces under UV light.

Carrying out the experiment

We used two UV LEDs with a wavelength of 275 nm to excite the fluorescence. The solution was placed in a quartz cuvette, which ensures that the UV light can penetrate completely through the solution. The light guide of our DIY spectrometer was positioned at a 90-degree angle to the light source in order to optimally record the emitted fluorescence. The resulting spectrum shows the characteristic fluorescence peak at about 450 nm, typical for aesculin.

Interesting facts about the fluorescence of aesculin

Aesculin absorbs UV light and emits it as visible light in the blue spectral range. This property is not only used in chemical analysis, but also in medicine, for example to mark microorganisms. The luminescent property of aesculin makes it an ideal molecule for experiments that teach students and other interested parties the basics of fluorescence.