You might contact Bruce Marx. He has sized samples. Perhaps he would send you a bit. James Osbourne Holmes a...@trail.com
-----Original Message----- From: Marshall Dudley [SMTP:mdud...@execonn.com] Sent: Thursday, October 28, 1999 11:22 AM To: silver-list@eskimo.com Subject: Re: CS>diagram/design You need a uv/vis scanning spectorphotometer. As the particles get bigger the absorption band wavelength gets longer. We use a Hack unit here for that. Unfortunately we have no way of calibrating it, so we cannot look at the spectrum and say the particles are such and such a size, all we can do is say that the particles in this batch are bigger or smaller than that, or that the particle size matches those in which the tests showed the highest effectiveness. If we could get samples that have been sized already by SEM or other means, we could calibrate it and then do a pretty good job of absolute sizing, but we have yet to be able to find such standards. Marshall James Osbourne, Holmes wrote: > HI Marshall, > > Can you explain how spectrophotometry can be used to indicate particle size > in the 1 to 10 nm range? > > They keep telling me It can't be done, at Spectronics. > James Osbourne Holmes > a...@trail.com > > -----Original Message----- > From: Marshall Dudley [SMTP:mdud...@execonn.com] > Sent: Thursday, October 28, 1999 9:43 AM > To: silver-list@eskimo.com > Subject: Re: CS>diagram/design > > Ivan Anderson wrote: > > > As far as I know EM and spectrophotometry will not differentiate > > between charged and uncharged particles. > > > > Ivan. > > Uncharged particle will tend to aggregate very rapidly, and > spectorphotometry will show the difference in particle size. I believe > there is therotical basis for there being a difference depending on charge > as well, but I will have to hit the references on that one to be sure. > > 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: > silver-list-requ...@eskimo.com -or- silver-digest-requ...@eskimo.com > with the word subscribe or unsubscribe in the SUBJECT line. > > To post, address your message to: silver-list@eskimo.com > > List maintainer: Mike Devour <mdev...@id.net>
