« on: 19/03/2014 20:23:50 »
Oh, and the reason the sulfur changes color has to do with vibrations in the molecule broadening the range of light frequencies that can be absorbed. Cold sulfur absorbs very strongly in the UV, but not in the visible. As the molecule warms up, this absorption broadens, extending into the visible range. When it absorbs only violet and blue light, the sulfur appears yellow. As it begins absorbing green and then yellow light, it shifts through orange to red, and finally it absorbs the whole visible range (though the peak is still centered in the UV region) and appears black.