sensitizing dyes for silver halide

[holo_cyware]

I'm exploring the possibility of makig my own silver halide plates; I'm mainly interested in 532 nm. And no, this is not about DCG.

I know about the pseudocyanine iodide as stated by Jeff B. but this is a bit expensive for my taste and I know there MUST be other cheaper dyes. Now, I'm aware that not all the dyes are good for silver sensitizing (metylene blue for instance due to the it's inability to stick to silver halides)

Somebody else already stated the rhodamine B. I personally may have found the indigo carmine as the spectrum absorption seems close to my laser frequency.

Any thoughts?

[Danny Bee]

I'm exploring the possibility of makig my own silver halide plates; I'm mainly interested in 532 nm. And no, this is not about DCG.

I know about the pseudocyanine iodide as stated by Jeff B. but this is a bit expensive for my taste and I know there MUST be other cheaper dyes. Now, I'm aware that not all the dyes are good for silver sensitizing (metylene blue for instance due to the it's inability to stick to silver halides)

Somebody else already stated the rhodamine B. I personally may have found the indigo carmine as the spectrum absorption seems close to my laser frequency.

Any thoughts?

a cheap dye that i use for green is Rhodamine b...its the best one i found for use with 532nm

[holo_cyware]

This is for Danny Bee: could you elaborate a bit please about the use of Rhodamine B?
Maybe something like Jeff's recipe + the amounts of Rh. B

Does anyone else have some experience with the Rhodamine B/silver halides plates?

[Hans]

Dyes are usually expensive if you look at the price per gram. But considering that you can dissolve one gram in 1 liter of Methanol and that for 100ml of emulsion you only need about 0.8ml of this mix, you can see that the dye will last you a very long time (100ml of emulsion can make 6 plates of 20x28cm if 2% gelatin is used). So the cost of the dye is actually much less than that of the very expensive AgNO3. 100 gram of AgNO3 nowadays costs around 200 dollar and you will run out of that long before you will even notice a drop in your dye stock solution.

Rhodamine B does work for green. I have used it to repeat Danny's experiment in cross-sensitizing red sensitive plates. But in theory the dyes below should work more effectively, and here is why:
Spectra for most dyes are usually given while in a water or methanol solution. These spectra look different though when they are used in an emulsion because in that case the dye molecules are adsorped onto the AgBr or AgBrI grains. On top of that some dyes have a tendency to form aggregates while adsorped onto AgBr. These aggregates also cause a shift in the spectrum of a dye.
As a rough rule of thumb one can say that the spectrum of a dye shifts about 30-50nm towards the red when adsorped onto a grain. The spectrum of Rhodamine shows a maximum of 540nm while dissolved in ethanol (http://omlc.ogi.edu/spectra/PhotochemCA ... mineB.html). So in an emulsion this spectrum will shift to the right and thus be less efficient than it might appear to be at first sight.

Here are some more alternatives for green light...

1,1'-2,2'-cyanine iodide for around: Around 550nm
3,3′-Diethyloxacarbocyanine iodide: Around 530nm
3,3′-Diethyl-9-methylthiacarbocyanine iodide: This is a very broadband dye. Works between 500 and 620nm with a slight maximum around 590nm. When subjected in high concentrations in an emulsion at high temperature the formed aggregates of this dye might further sensitize into the deep red.

[Hans]

Here's another dye that works:
trans-4-[4-(Dimethylamino)styryl]-1-methylpyridinium iodide: Around 520nm