coyote wrote: > On that note, My friend says the light shift effect, at least in atmospheric > application, is due to [UV] light accelerating particles and the color will > always shift downwards into the less energetic as the particle absorbs > whatever frequency of light that accelerated it. I presume that yellow is a > less energetic frequency than UV? Shifting to red is certainly common enough > in the sky.##
There seems to be some confusion here. I will try to clear it up. There are two effects here with respect to CS. One is the Tyndall effect. In this effect very small particles will scatter light, and the amount of scattering is wavelength dependent. For very small particles, blue light will be scattered the most and red the least (and wavelength in between will be scattered between the two according to wavelenth). This means that direct rays of light will be depleted in the scattered wavelength appearing red/yellow, and the sol/sky will appear the color of the scattered wavelength. A couple of examples should help. For the sky, the blue is scattered, thus giving us a blue sky. The remaining light will be more richly left with the yellow/red wavelengths, so the sun appears yellow, and as it goes through more atmosphere at sunset, will appear orange or even red. The beautiful colors you see on clouds near sunset are then due to the illumination of these separate sources of light, and their interplay with each other, some parts of the cloud shadowing other parts, so that which is directly illuminated by the sun will be yellow/orange/red, and that shadowed will have a blue/violet cast to it. If you look at skim milk it appears to have a blueish hue to it. This is due to the enhanced scattering of blue light by the milk particles. Now getting back to CS. In most concentrations of CS the tyndall effect is not nearly as strong as the absorption effect. So you will not likely see much color from this effect. However, small particles of silver absorb light quite strongly at a wavelength which depends on particle size. Atoms absorb in the uv region, and as the particle grows, absorption moves to longer wavelengths, ie. blue, green, yellow, orange, red. What you see will be what is left, which is the complement of the color absorbed: absorbed = appearance uv clear blue yellow green orange yellow red orange green red blue infrared clear For CS you will typically see the first two in the series, clear and yellow, sometimes you will see the 3rd as well, orange. But once you get to the red, green and blue, you will typically have a broad range of smaller particles with the larger particles, which will cause colors to be absorbed across the spectrum, making it appear brown, gray or black. Bless you, Marshall -- The silver-list is a moderated forum for discussion of colloidal silver. To join or quit silver-list or silver-digest send an e-mail message to: [email protected] -or- [email protected] with the word subscribe or unsubscribe in the SUBJECT line. To post, address your message to: [email protected] Silver-list archive: http://escribe.com/health/thesilverlist/index.html List maintainer: Mike Devour <[email protected]>
