From: Katharine Thayer (kthayer@pacifier.com)
Date: 04/03/02-09:39:13 AM Z
This is very useful, Sandy, thanks.
Sandy King wrote:
>
.
>
> For what it is worth I do have some information on the spectral
> sensitivity of platinum and palladium. The information is found in a
> chart entitled Quantum Yields for the Photolysis of platinum and
> palladium with ferrous salts, which of course is the light sensitive
> chemical for kallitype as well as palladium and platinum. The chart,
> which was sent to me by Eric Neilsen, provides information for
> Quantum Yield and Fraction of Light Absorbed by ferrous salts at
> specific wavelength in nanometers. Although the chart requires some
> interpretation one can easily infer from the data that both platinum
> and palladium have their greatest sensitivity at about 254-313
> nanometers, with a very gradual drop-off in sensitivity beyond that
> all the way to about 510 nanometers, and with a very sudden an
> precipitous drop-off in sensitivity beyond 510 nanometers to
> virtually none at 620 nanometers.
>
> What one can infer from this information is that the spectral
> sensitivity of platinum and palladium, although very great at 350-370
> nanometers, as is the case with dichromate colloids, has much greater
> sensitivity than the colloids between 400-500 nanometers, which may
> explain why platinum and palladium work about equally well with both
> BL/BLB and Super Actinic tubes, whereas the dichromate colloids test
> slower with the SAs, at least in my experience.
>
> I don't know the name of the book this chart was taken from but I
> suspect that Eric can provide that information.
>
> Sandy King
>
> --
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