Just a quick reply to say Thanks for *both* your responses Marshall.
I'll break them down when I've gone through them and may get back to you at a later date. Cheers N. > Date: Tue, 13 Apr 2010 15:26:10 -0400 > From: mdud...@king-cart.com > To: silver-list@eskimo.com > Subject: Re: CS>where is everyone?/..."TAITP~WBSF"? > > The strength of the Tyndall "I", that is the intensity of the scattered > light to the light beam is given by the following equation: > > I = kNV^2/w^4 > > where N is the number of particles, V is the volume of each particle, > and w is the wavelength of the light. From this we can see the following: > > If a particle doubles in diameter, its volume will go up by a factor of > 8, and the intensity of the Tyndall from that particle will go up by 8^2 > = 64, so the Tyndall goes up by the 6th power of the diameter. However, > if you are comparing the same ppm solutions with different particle > sizes, the number of particles will go down by a factor of 8, if you > double the size. Thus the intensity of the Tyndall from two colloids > with the same ppm, but a 2:1 difference in particle size will be 8:1, > that is it will vary to the 3rd power. That is why a bright Tyndall is > usually more indicative of particle size than concentration. > > Now for a typical colloid the wavelength, is more dramatic. The > intensity will vary inversely by the 4th power of the light's > wavelength. For example, if you take blue laser of 330 nm and a red one > of 660 nm, that ratio will be 2:1, and the intensity of the Tyndall from > them would be that the blue one would be 2^4 or 16 times brighter. > > Now from this is appears that the ratio of light scattered from small > and large particles will have the same ratio independent of the > wavelength of the light. This is true for the general case of most sols > which are of non-conductive particles. However silver and gold are > different, being very good conductors, they have resonances, somewhat > like an antenna. As it turns out silver particles of the following > sizes will have the following maximums on the Tyndall wavelengths: > > 38 nm - 470 nm > 47 nm - 490 nm > 90 nm - 560 nm > 118 nm - 600 nm > > The fwhm of these runs approximately 1/2 of their peak wavelength. > > If you look at > http://products.mercola.com/Images/home-tanning-beds/wavelength-chart.jpg > to see what colors the wavelengths are we find that red and amber sill > scatter much more by the 118 nm particles than the blue, and that for 38 > nm particles, they will scatter blue better. From the chart I have the > ratio is rather large, 5:1 for the 38 nm between blue and amber and > almost 5:1 for the 118 between amber and blue. Thus there is a 25:1 > difference between these two wavelengths and particle sizes. So it does > appear by using different colored light, and Tyndall intensity, to get a > crude handle on particle size and concentration over and above the > "color" of the sol. Only problem is that when the particle sizes get > below 30 or so nm, they both absorb and scatter UV light which cannot be > seen at all. > > Marshall > > > > Neville Munn wrote: > > Now you're touching on a subject that I've been pondering for a while > > but can't seem to find anything of value to read in the public domain. > > > > You mentioned red laser becoming less apparant, but 405nm blue DOES > > show up. I'm still curious to know if there are any methods of home > > determination of particle size approximation using laser lights, red > > or green or blue or whatever other colour which *could* indicate a > > particular nm range in the colour spectrum. If light can be used to > > determine approximate particle size is it possible one can make use of > > differing laser colours to approximate particle size in solution? > > > > Praps you could help me out with this: > > > > I got three red lasers, > > (1) 650nm+/-10 maximum output 1mW.......{bright beam passing thru liquid} > > (2) 650nm+/-10 maximum output 5mW.......{beam of lesser brightness} > > (3) 630-650nm maximum output 1mW........{no beam at all} > > > > Is there anything you can tell me regarding the differences in beam > > strength between these lasers, all shone thru the same solution? > > Particularly the last one with no beam at all. > > > > N. > > > > ------------------------------------------------------------------------ > > Date: Tue, 13 Apr 2010 00:44:19 -0700 > > From: dokdal...@yahoo.com > > Subject: Re: CS>where is everyone?/..."TAITP~WBSF"? > > To: silver-list@eskimo.com > > > > > > FYI: Using a Blue 405-nm Laser, or even Green > > LD...can-detect smaller...Size! > > Have gone down to 385-nm (non-laser) light source, using special TRIX > > & PMT. > > (Not sure Particle(s) Size PEAKING at 405 nm, but-maybe...Marshall knows?) > > > > > > Tyndall will become LESS apparent (using RED), but 405~Blue > > still Detecting! > > > > As long as it's only-slightly Yellow (and don't Smell/Taste > > like P*ss), it's GQQD > > to use for ANY application you wanted, but for INTERNAL > > use...It's UP-to user? > > > > > > > > > > > > ------------------------------------------------------------------------ > > Looking for a hot date? View photos of singles in your area! > > <http://clk.atdmt.com/NMN/go/150855801/direct/01/> > > > -- > The Silver List is a moderated forum for discussing Colloidal Silver. > Rules and Instructions: http://www.silverlist.org > > Unsubscribe: > <mailto:silver-list-requ...@eskimo.com?subject=unsubscribe> > Archives: > http://www.mail-archive.com/silver-list@eskimo.com/maillist.html > > Off-Topic discussions: <mailto:silver-off-topic-l...@eskimo.com> > List Owner: Mike Devour <mailto:mdev...@eskimo.com> > > _________________________________________________________________ If It Exists, You'll Find it on SEEK. Australia's #1 job site http://clk.atdmt.com/NMN/go/157639755/direct/01/
