Nitrogen dioxide light absorption

Nitrogen dioxide (NO2) is a brown/yellow gas at room temperature due to its light absorption in the blue spectral region. Nitrogen dioxide has a very irritating odor and is fairly toxic. It is produced by the oxidation of NO, but NO2 also photolyzes back to NO ... 

The adhesion of RFL-coated tire cords to rubber can be adversely affected if the dipped cords are exposed to ozone, UV light, nitrogen oxides, sulfur dioxide, or air before vulcanization into rubber. lyengar proposed that ozone exposure of RFL reduces adhesion because ozone attacks the double bonds of the butadiene component of the rubber latex and impairs its cocuring with the solid rubber compound. Infrared studies by Solomon reinforced this argument. When typical RFL films were exposed to ozone, the IR spectrum showed an increase in IR absorption at 1720 cm corresponding to an increase in the carbonyl content in the exposed film. An RFL film with no ozone exposure did not show this absorption at 1720 cm The increased carbonyl content is due to the reaction of some double bonds in the rubber with ozone and therefore, would leave fewer unsaturation sites for rubber crosslinking and adhesion. 

---