Little Bang Posted January 28, 2011 Report Posted January 28, 2011 Gold appears yellowgold because the electrons of the gold atoms absorb and re-radiate that frequency? Quote
modest Posted January 28, 2011 Report Posted January 28, 2011 Gold appears yellowgold because the electrons of the gold atoms absorb and re-radiate that frequency? Metallic gold absorbs blue light (the high end of the visual spectrum) and reflects the mid and lower end of the spectrum. Interestingly, in metals like silver and lead, mostly ultraviolet light is absorbed meaning that the entire visual spectrum is reflected to an equal degree making them look grayish due to the frequency of their 4d→5s electron jump. But, gold is heavier and its 5d→6s transition energy is lower because of relativistic effects shifting the absorption frequency lower and making it absorb blue light and therefore reflect gold light. That gold appears goldish is therefore a test of special relativity's treatment of mass/energy—a test which it passes. ~modest Quote
Little Bang Posted January 29, 2011 Author Report Posted January 29, 2011 Any explanation of this? http://www.scientific.net/MSF.620-622.509 It appears that the reflected frequency can change as the particles of gold get smaller, around a hundred nanometers.I wonder how QM deals with this? Quote
modest Posted January 31, 2011 Report Posted January 31, 2011 Any explanation of this? http://www.scientific.net/MSF.620-622.509 It appears that the reflected frequency can change as the particles of gold get smaller, around a hundred nanometers.I wonder how QM deals with this? I'm not sure. I can't see the whole paper and I don't know much about the properties of photosensitive glass. Sorry. ~modest Quote
Turtle Posted January 31, 2011 Report Posted January 31, 2011 I'm not sure. I can't see the whole paper and I don't know much about the properties of photosensitive glass. Sorry. ~modest PBS's Nova series mentioned this very thing last week in one of their programs. it wasn't photosensitive glass, but rather stained glass. gold finely divided enough and added to glass, makes red or pink glass, not the 'yellow' one might expect. i can't find a transcript but here's a link to an online video of the show. i don't recall it being any problem for qm. Making Stuff Smaller Quote
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