Ode Coyote wrote: > "Scientists studied the absorption spectra of the different preparations > to pinpoint their shapes. "Spherical nanoparticles absorbed in the blue > region of the spectrum, for example," Yacaman said." > > ## So, "color" isn't 'entirely' about size, but is something much more > complex especially when shapes of impure crystals can vary in a fractal > pattern according to the nucleating particle center that the crystal grows > upon.
Yes, this is known, and covered in some of the references I have posted in the past. Basically a silver particle is like a small antenna, and will have a resonant frequency. Light at the resonant frequency will be absorbed, and as the particle increases in size, then the resonant frequency decreases (resonant frequency will be 4 times the length of time it takes for electricity to travel from one margin of the crystal to another, just like with a 1/4 wavelength antenna), moving the absorption band from uv, to violet, blue, green, yellow, orange, red, and infrared as the crystal grows larger. The apparent color is of course the complement of the absorbed color. Now if you make an antenna in the shape of a snowflake, you will have a myriad of resonances, some low frequency across the whole flake, but others within the center, arms and areas at the end of the arms, each having their own resonances, and these will all be much higher resonances than the one across the whole thing. Exactly the same thing happens with silver crystals, except the frequencies are not in the radio range, but the light ranges. The physics is actually quite well understood, although computing all the resonances for an irregular shape becomes difficult if not impossible. Marshall -- The Silver List is a moderated forum for discussing Colloidal Silver. Instructions for unsubscribing are posted at: http://silverlist.org To post, address your message to: [email protected] Silver List archive: http://escribe.com/health/thesilverlist/index.html Address Off-Topic messages to: [email protected] OT Archive: http://escribe.com/health/silverofftopiclist/index.html List maintainer: Mike Devour <[email protected]>
