Clinton A Oakley. Victoria University of Wellington. Generally plastic cuvettes strongly absorb UV, which is why they cannot be used in spectroscopy in the UV range. Readings with UV light are We can see visible light emitted by the sun. But the sun also emits light we can’t see, including UV light. Quinine is a substance found in tonic water that is sensitive to UV light. It can absorb UV light that we can’t see and then re-emit visible blue light that we can see. This process of converting ultraviolet into visible light is “crown” glass, monomer plastic (CR-39 ®), and polycarbonate plastic (see Table 1). Lenses made from crown glass provide excellent optical properties (as indicated by the high Abbe value). Crown glass is more scratch resistant but heavier and less impact resistant than plastic. Glass absorbs some UV light; however, Titanium dioxide (TiO 2) is one of the most important pigments. It is widely used because it efficiently scatters visible and absorbs UV light, thereby imparting whiteness, brightness, and opacity when incorporated into a plastic. TiO 2 is commercially available in two crystal structures—anatase and rutile. Rutile TiO 2 pigments are preferred Plastic’s generally low density means these fragments can easily be picked up by winds and blown around the These particles scatter ultraviolet and visible light and absorb infrared light It is again observed that UV exposure does not appreciably change the melting point of the polymer. All samples exhibited, irrespective the aging and the carbon black amount, the melting point at ~130 °C suggesting that addition of carbon-black work as a light stabilizer and U.V shielding by protecting the polymer from getting degrade [36]. Absorbance of UV light by trans-azobenzene (a π→π* transition) leads to isomerization to cis-azobenzene. Contrariwise, absorbance of visible light (blue light) by cis-azobenzene (the n→π* transition) results in conversion back to the trans-isomer [so does leaving cis-azobenzene in the dark, a process known as thermal relaxation]. The Different molecules will absorb different wavelengths of light. The wavelengths of light for UV-visible absorption are from about 200 nanometers to 800 nanometers. This is a section of the electromagnetic spectrum pictured. Absorption of light starts with energy of a certain wavelength in this UV-visible region being exposed to a molecule. ZhNpg.