The Chemistry of Art > 2. The Structure of the Atom and Colours > The Relationship Between Absorption And Reflectance Spectra >
The relationship between absorption and reflectance spectra and the effect of infra-red and ultraviolet light on pigments including zinc oxide and those containing copper
Relationships:
- Absorption:
- Appears as black spectral lines within full spectrum
- Percentage of light absorbed at each wavelength
- Signifies which photons have been observed and hence which frequencies of visible light have been absorbed
- Reflectance:
- Percentage of light reflected at each wavelength
- Substance exhibits colour complementary to that color of absorbed particular wavelength.
Effects of Infra-red (IR) lights on selected compounds/substances:
- Zinc oxide changes from white to lemon yellow (returns after cooling)
- Red Copper (I) oxide changes to black Copper (II) oxide
(permanent change due to substance breakdown)
Effects of Ultraviolet (UV) on selected compounds/substances:
- Zinc oxide (ZnO) fluoresces as pale yellow under the presence of UV light
- Green malachite (CuCO3 . Cu(OH)2 ) fluoresces dirty mauve colour