Pure water and tap water exhibit good transmission characteristics for light with wavelengths between 250 and 800 nm. The transmittance of 5mm thickness is above 80%. After the wavelength is shorter than 250 nm, the light absorption rates of both increase rapidly. Especially tap water has a stronger absorption of<250 nm light. 2.4cm attenuation to 70%; 8.5cm attenuation to 30%; Attenuation from 16.3cm to 10%
On the basis of the effective distance topic, how far does UVC ultraviolet radiation penetrate in water? Everything still returns to the concept of bond energy. In water molecules, the bond energy of the H-O bond is 485 kJ/mol, corresponding to 4.98 eV, which is approximately 249 nm. Therefore, when testing the transmission spectrum of pure water, the absorption edge begins to decrease around 249 nm. Based on this data, it can be said that normal drinking water with less impurities, such as tap water, does not have strong absorption of 275 nm UVC-LED. UV sterilization devices based on UVC sterilization principles can kill at long distances
The most important consideration should be the rapid divergence of light during propagation, which leads to a sharp decrease in intensity at the far end. Half sphere small angle packaging is actually very common in the UVA industry, which also applies to UVC packaging. Small angle light output can allow UVC to propagate further, making it very suitable for manufacturers such as water cups, long water tanks, and overcurrent water sterilization devices
The high environmental humidity does not cause significant absorption of UVC, which means that even in the sauna room, UVC ultraviolet rays can be used for real-time sterilization.