Bart;Originally Posted by bart Nadeau
Yes, the addition of sensitizing dye can make an emulsion sensitive to any particular portion of the spectrum you wish including infra-red. A raw emulsion is mainly UV and Blue sensitive.
Most silver has impurities in it that will make it unusable for photographic emulsions. It would depend on the silver and on the nitric acid. Reaction of silver metal with nitric acid, IIRC, requires red fuming nitric acid as silver is a noble metal. RFNA, as it is called, is rather hard to get and gives off very toxic fumes.