Sciencemadness Discussion Board

Visible silver particles?

YT2095 - 15-11-2007 at 04:29

I`m not sure if this belongs in Here or Energetic materials, but anyway...

I`m conducting an Old experiment, that consists of making my own photographic paper (coffee filter paper soaked in silver nitrate and then NaCl soln and allowed to dry).
now this works great in sunshine (reacts in Minutes).

but what I`m doing is using and Isotope to expose this paper that is in a dark envelope, with a wire mesh on that and then the Isotope.

I`m hoping that if it works I`ll get a clear(ish) mesh pattern appear on the paper.

this sample I have gives off 1200 DPS, and I calculate that over a week I should have nearly 73 million "hits" to the paper.

would that be Visible at all?
it Sounds like a lot of hits, but in atom sized silver particles it isn`t really that much I don`t think.

the area it will be over is roughly 3cm x 3cm.


it`s also in a Light and air tight box, I`m wondering if Radon may make the paper blurry also, as it`s resting at the bottom of this box.

I`m sure Someone here has done all this before and knows the score, and can hopefully provide a little help/guidance.

if it works, I`ll put some pictures up also! ;)

woelen - 15-11-2007 at 05:14

Assuming that DPS stands for decompositions per second, and that one particle appears per decomposition I find roughly 104 million particles per week. How much of these hit the paper is not easy to tell, but let's assume 25%, then you'll have 26 million hits per week.

This is an amazingly small amount. If you think about the number of atoms in a mole, which is 6.02*10^23, then you see that you only have in the order of 10^(-16) to 10^(-15) mole, which is in the order of magnitude of 0.01 picogram to 0.1 picogram. I would be surprised if you see any difference between the exposed area and the rest of the paper. A picogram is VERY VERY small.

YT2095 - 15-11-2007 at 05:26

well I don`t know the Total DPS as in all 720 degrees of the isotope, the 1200 count is from a single side of it.

it will penetrate and pass through lead though 3mm thick.

woelen - 15-11-2007 at 05:50

If it passes through lead 3 mm thick, then only a tiny fraction will be captured by your AgCl-paper and then the situation is even worse.

I am afraid that it hardly will be visible. With a developer (such as hydroquinone + Na2SO3 + metol) things can change a lot. A single silver atom, excited by light (or other radiation) acts as a nucleation spot, where the developer attacks the silver chloride much more easily than on other places. This is the basis of photography. The silver particles themselves are invisible, but they allow much faster reduction of nearby AgCl, compared to other AgCl. These invisible silver particles form a so-called "latent image". Search google for "latent image", one fairly good link is this one: http://en.wikipedia.org/wiki/Latent_image

Hopefully this helps and gives some more understanding. This is very interesting matter. Even better results are obtained with mixed AgCl/AgBr deposits.

YT2095 - 15-11-2007 at 06:12

that`s Great help thanks :)

I have the Hydroquinone and sodium sulphate is easy enough to knock up in a few mins.
I considered the Bromide also, but not having a Proper "dark room" in which to dry these papers or handle them, I figured the Chloride would be best as it`s pretty forgiving to low light and short exposures, I think the bromide is more sensitive.

I think maybe the best thing I can do is Check it at the end of the week and see if there Is any change, and if not leave it for Longer.

it`s not really costing me anything to do this, only filter paper and some space.

and although I`m excited about hopefully getting a result, I`m more than Patient when need be.

woelen - 15-11-2007 at 07:39

"I have the Hydroquinone and sodium sulphate is easy enough to knock up in a few mins."

No sulfate, but sulfite must be used. It also is important to use normal sulfite and not a bisulfite. The solution should be mildly alkaline, otherwise it will not work.

YT2095 - 15-11-2007 at 07:58

aha yes, I didn`t see the 3 and assumed 4, Thanks, My Bad :)


NaOH soln and SO2 bubbles though it? should work I believe?

woelen - 15-11-2007 at 08:18

Do you have bisulfite? If you have that, use some excess Na2CO3 or K2CO3 and the bisulfite. You also could bubble SO2 through a solution of Na2CO3, but that is more hassle. For SO2-production you could use copper wire in H2SO4, although a large excess of H2SO4 is needed. Using Na2CO3 instead of NaOH assures that the solution is only mildly alkaline, otherwise it is strongly alkaline.

Hydroquinone in a strongly alkaline solution really sucks. Just for fun, try it. The hydroquinone then is oxidized by oxygen from air within a few minutes, it really sucks oxygen from the air and before your AgCl is developed, the hydroquinone already is spoiled if the pH is too high.

For developing a print of 10x15 cm, you only need 100 ml or so of liquid, with only 100 mg or so of hydroquinone added and a gram or so of sulfite. Solutions only need to be dilute.

YT2095 - 15-11-2007 at 08:55

I make the SO2 in a Large flask, it has a spoon that I put Sulpher onto and light, this then goes into the flask and the air pipe feeds the flame and the pipe Out has the SO2.
it`s nothing fancy, just something I made myself with some glass tubing a fish tank pump and some scrap SS metal bits, but it serves me well :)

I don`t have any bisulphite at all, so I shall have to make some, but`s good too and I don`t mind doing that :)

that High PH and HQ sounds like a nice way to make Nitrogen! (if you ignore a little Argon).

I have all these carbonates (and more) that you mention, and I have at least 1 week to make some of these things needed, I think it will add Extra appeal and interest to the project when you consider that even the Silver Nitrate was made by me and the photo paper etc...

Really RETRO-TECH :)

garage chemist - 15-11-2007 at 10:03

The SO2 gas that you make should better be free of oxygen, since oxygen rapidly oxidises solutions of sulfites.
This is a big problem in industrial production of sulfites, here the residual oxygen in the sulfur burner gas quantitatively reacts with the sulfite, leading to a considerable loss. Pure SO2 gas would be uneconomic to use due to its much higher price, and sulfur stops burning if the oxygen content of the gas drops below a certain value.
They separate sulfite and sulfate by fractional crystallization (Na2SO4 as the decahydrate, by cooling) and sell the sodium sulfate byproduct as well, after refining to normal purity standards.

I recommend you to buy some sodium disulfite (also called metabisulfite or pyrosulfite), it is a highly useful chemical, especially in inorganic chemistry.

The only good way to make sulfites at home would be to liquify SO2 from the burner gas using dry ice, or using a different chemical method to make pure SO2 (like reduction of H2SO4 with copper or other metals- gives useful byproducts depending on what you use) for reaction with your base.



[Edited on 15-11-2007 by garage chemist]

YT2095 - 15-11-2007 at 10:19

I have Kipps apparatus here, it probably wouldn`t take too much effort to "fire it up" and get it working again.
although the acid, does it have to be Conc sulphuric? I only have about 500ml of that left!

I have also Campden tablets, they give off SO2 when added to water, theyr`e used as sterilisers in Beer or Wine making.

garage chemist - 15-11-2007 at 11:46

I would hardly call a Kipp suitable. The reduction of H2SO4 requires strong heating. Just use a normal flask or erlenmeyer.

500ml is plenty, you'll probably need only 50ml to make the SO2 you need.

unionised - 15-11-2007 at 12:25

Campden tablets are mainly bisulphite anyway, you might be able to use them directly.

woelen - 15-11-2007 at 23:40

Yes, the campden tablets are almost pure K2S2O5. I have the powder form of this and it states as the ONLY ingredient potassium metabisulfite. But if you are not sure, then use these tablets to make SO2. Mix 1 volume of H2SO4 with 1 volume of water (careful, hot!!) and then add crushed tablet. Slight heating is required (60 C or so). SO2 is bubbling off.

But, first I would try directly, dissolving some of the crushed tablet in a solution of Na2CO3, keeping the solution alkaline.

But as garage chemist did, I also really recommend you to either buy sodium sulfite by the kilo (available from silverprint) or some metabisulfite (available at shops, who have wine making stuff, the usually carry the potassium salt). Sulfite (or one of its variations) is one of those chems, which I really consider a baseline chem and which should be present in a serious home lab.

YT2095 - 17-11-2007 at 07:21

ok, I went out today and got a pretty good deal on some proper 35mm film, 3 rolls for 97p!
ok it`s a little out of Date sure, 9/07.
but it`ll probably do a better job than my coffee filter paper and Silver Chloride I expect.

it`s a 36 shot film and ISO 200/24(degree symbol) 135DX/36 whatever that means??? (sounds like a Processor spec! LOL).

so my plan is to get somewhere totally dark, unravel this film and cut it into single sheets and then store them in a light tight tin, and take them out as I need them and put then in black paper and try from there.

I`m assuming I will need the same stuff to develop them???

the Good part is that I have a projector that will show these negatives so I may be able to see more detail than I would with my filter paper method :)

unionised - 17-11-2007 at 08:29

135 is the size/type of film cassette DX means there's a coding on the edge of the film to tell suitably equipped camaras what film speed it is and 36 is the number of exposures.
http://en.wikipedia.org/wiki/DX_encoding

This could be a dumb question; is it monochrome or colour film?
The developers for colour film are more complex.

Also I just wondered, if you put a few layers of the film on top of eachother before exposing them would they have a better chance of catching the gammas and recording an image?
(It might be a bit tricky to keep them lined up)

YT2095 - 17-11-2007 at 08:48

not dumb at all, it`s a Color film.

Samsung Prime Color Film, to be exact.

your Layering idea is Good actually, I expect that with alu plates or maybe even thin lead, it might be possible to create a 3D type of effect, a bit like a CAT or MRI scan?


[Edited on 17-11-2007 by YT2095]

unionised - 18-11-2007 at 03:04

I'm not sure how you would develop the colour film. Taking it to the local photographic shop and saying it's a radiograph might get some funny looks.
I would try to find some black and white film on ebay.

YT2095 - 23-11-2007 at 04:17

well for the Original experiment with the silver chloride paper I made, it`s failed entirely, there`s not even a Trace of exposure, and what`s worse is that when I took it out the black envelope it was Wet too.
the Sodium nitrate part has obviously taken in moisture from the air and ruined it (assuming there was anything to ruin).

nevermind, I`ll know better for Next time ;)

woelen - 23-11-2007 at 05:59

Color film development is VERY different from B&W development. You need a rather extensive set of rare chemicals, which are hard to obtain. Color films have different dyes in the emulsion layer, which are developed by light of different wave lengths. This makes color development a rather picky process, which only works under highly controlled conditions (e.g. temperature control with an accuracy of 0.1 C or so) and for this reason only the most experienced and advanced hobby photographers do color development at home. It is possible, but not easily done.

YT2095 - 23-11-2007 at 06:14

so basically I`m doomed then unless I get hold of some B/W photo paper.

not_important - 23-11-2007 at 07:06

You can develop colour film as B/W, it is still a silver halide base material. The colour part uses the byproducts of developing the silver to couple with chemicals in the developers to form dyes. If you did around on the Net some I suspect you'll be able to find some information on that.

For DIY, these might be useful

http://www.artic.edu/~fendsley/altProc_SaltPaper.html

http://www.alternativephotography.com/process_albumen_paper....

http://unblinkingeye.com/Articles/Emulsion/emulsion.html
http://www.apug.org/forums/forum205/32860-notes-account-maki...

http://www.iop.org/EJ/abstract/0950-7671/23/5/304

http://www.archive.org/details/chemistryofphoto00harruoft


Real world books that could be of interest

http://www.christopherjames-studio.com/build/thebook.html

Photographic Emulsion Technique
http://www3.interscience.wiley.com/cgi-bin/abstract/11276696...


Note that the old plates and less modern print material are rather insensitive. Your 1200 DPS source could take weeks to months to expose. When I was young I had a 'science kit' that included a radioactive source, probably a few hundred DPS; the experiment making what you want to do took a couple of weeks of exposure using B/W sheet film.

YT2095 - 23-11-2007 at 07:52

That`s Fantastic news! Thank You! :D

I got a little concerned for a while because I was considering buying More of these films, and although they`re not expensive it would have been quite wasteful.

I`ve got all morning free tomorrow, so I`ll go through those links and take a few notes as well as finish my Dark room and red light array (I`ll be using LEDs).

would I be correct in saying that I will need to wear gloves while handling the raw unexposed film, and also will I be able to see the marker between each shot? this a 36 picture film, will the line between each be clearly visible in red light?

I want to cut the film into single plates so I can use them one at a time, the reason is that a Radiation source may affect the entire roll just for taking one picture, so a single piece of film per exposure would be best.

not_important - 23-11-2007 at 07:57

Quote:
would I be correct in saying that I will need to wear gloves while handling the raw unexposed film, and also will I be able to see the marker between each shot? this a 36 picture film, will the line between each be clearly visible in red light?


No, the emulsion coating is continuous, the frames that show up after developing are caused by unexposed film.


I'd find some instructions on developing colour film as B/W before buying any more, though.



[Edited on 23-11-2007 by not_important]

YT2095 - 23-11-2007 at 08:08

this just gets better then! so I may even get 37-38 slides from it :)
and even try a 360 wrap around to get a complete idea of emissions from this "hot rock"

and thinking about it color would be a little useless anyway for this type of picture.

UnintentionalChaos - 26-11-2007 at 22:23

You will need actual black and white film for this. I have done some B&W work before and it shouldn't be too hard. If you try to develop color film in B&W chemicals you got nothing...I've seen someone try...See if you can get Kodak Tri-X film. It should run about $5 for a 36 (actually 37 or 38 frames usually) shot roll which isn't too bad. You wont be able to use red light to see the unexposed film. It is extremely sensitive and any light will expose it. When I worked with some rolls of it, I used a pitch black closet. Sit in there for 5 minutes. If you can see light coming in at all, it isn't dark enough. Stuff towels into the crevices around the door if necessary. Developing single pieces will be a lot harder than a whole roll since you can't look at the film until it has been processed and pieces touching during processing will ruin it. Doing it individually will mean that one frame will take you @30 minutes...only 18 more hours to go. Maybe you can gut a cheap camera for film advancing capability and build some lead shielding for it to give it a shutter. The film can then be processed normally. Ask any local colleges if they have a B&W photo lab. Quite a few do, but getting access is the hard part.

YT2095 - 26-11-2007 at 23:59

Quote:
Originally posted by UnintentionalChaos
Ask any local colleges if they have a B&W photo lab. Quite a few do, but getting access is the hard part.


actually that`s a Great idea! I`m at college all day on Tuesdays and I get on very well with my lecturer and the Lab staff, maybe I might even be able to do an exchange of some sort, these 3 color rolls for a couple of sheets of B/W paper and Q&A session :)

I never considered asking there, Thanks! :)

JohnWW - 28-11-2007 at 17:22

B&W film, with AgCl or AgBr as a fine emulsion in gelatine, is stlll used, in large sheets, for X-rays. Only the negatives are usually developed, B&W paper not being used for the purpose.

YT2095 - 20-12-2007 at 03:28

update, I have all the B&W paper and all I need to develop them, I`ve even done test photos with a little pinhole camera I made and they work fine.

I`ve had the paper in an envelope with the isotope ontop of that and all put in a light tight tin for exactly a week.

it totally failed to show Anything at all :(

I so wanted it work, but but sadly it`s a Zero result that way.
I think Next I should try again but this time use a Phosphor as an Intensifier.

YT2095 - 27-12-2007 at 06:05

I`V DONE IT!!!!!!

I`v finally got my X-Rays! here, check these out...





the strange patterns you can see from the Ra sample are from the tiny glass vial I keep it in.
the Th is pretty self evident, it was a piece of Th metal in a thin plastic bag up against the film.

it`s quite plain to see also that the Ra is much "Hotter" than the Th in way of Gamma.

Thanks each for the great ideas and tips given me in this thread (and also via PM ). ;)

[Edited on 27-12-2007 by YT2095]

woelen - 27-12-2007 at 07:41

Nice to see that kind of results! How long did you expose the paper to the radiation of the samples, before you developed the paper?

[Edited on 27-12-07 by woelen]

YT2095 - 27-12-2007 at 08:05

exactly 1 week to the hour.

I`m thinking now that perhaps 2 weeks for the Th to get any usable X-Ray pics and maybe 4-5 days for the Ra sample as it looks a bit saturated at the one point.

YT2095 - 27-12-2007 at 12:10

I`ve just set another exposure up, I`m using the Th metal again as it`s a nice an uniform shape, but this time I have sellotaped 2 sewing needles to it and then presented it to the photo paper, so hopefully I maye get an interesting picture of this.
I plan on leaving this for 2 weeks exposure time.

I still cannot understand WHY that Monazite rock didn`t give Any result at all though????? I know that 1200 DPS isn`t much, but it WILL give a count through Lead plating and the Th and Ra will not???

it simply doesn`t make Any sense at all to me?

woelen - 28-12-2007 at 10:41

An exposure of just 1 week? That sounds like high sensitivity of the paper. I have read in my old book (Grundlinien der Chemie, Ostwald, 1919, Dresden) that the first discovery of radioactivity was after storage of a uranyl salt near some photosensitive plate for many months.

I also do not understand the geiger counting throug lead plate, while on the other hand, no image can be obtained with the monazite rock. The only thing I can imagine is that the monazite rock gives off very fine dust, which disperses into the air and so it goes around the lead plate to the Geiger counter.

YT2095 - 28-12-2007 at 11:05

it can`t give off dust, it`s in a small zip-lock bag with no apparent holes in it.
and like yourself, I cannot understand this either???

and yes exactly one week to the very Hour itself. the paper is plain Multigrade Ilford IV FB Fiber.
in B&W, I have no real idea how to judge sensitivity as this is all quite New to me, I will say that a Pinhole cam takes 1 hour to make a negative in overcast cloudy weather during the day.

as for the GM counter, (not all that sensitive either) yes it picks it up quite well through 2 sheets of roofing lead (and no the lead alone gives no count) I don`t get the 1200 DPS through is, closer to a tenth of that.
AND it will pick it up from several feet away too!

but it will not expose my paper!??????

YT2095 - 10-1-2008 at 03:44

as promised, 2 weeks later here is the x-ray of 2 sewing needles:



it`s not a Great picture and looks better in real life, but you may just be able to make out the eye of one of the needles on the right.
you can clearly see the band across the middle where I sellotaped them into place on the isotope.

not_important - 10-1-2008 at 07:46

Quote:
...
I also do not understand the geiger counting throug lead plate, while on the other hand, no image can be obtained with the monazite rock. The only thing I can imagine is that the monazite rock gives off very fine dust, which disperses into the air and so it goes around the lead plate to the Geiger counter.


Think of the decay chain. Pure thorium or its compounds give off 4 MeV alphas in decay. The decay chain products, which will have built up in any decently old mineral sample, give off a number of different particles, including roughly 2 MeV betas.

Then there are the photos emitted by the decays. Pure natural thorium gives off a range of x-rays, and has a couple of gamma peaks at (I believe) 60 and 140 KeV. The decay chain products include gammas in the 500 and 900 KeV range, plus some around 2.6 MeV.

With a 14 Gy half life, purified thorium won't have built up much decay products. Also, monazite often contains some uranium, which adds to the decay spectrum.

Here are several charts of the decay energies of the natural thorium decay chain. Note than in the third reference the top intensity gammas do not come from the parent 232Th decay, a purified thorium compound or the metal will be lacking in these decays.

http://hepwww.rl.ac.uk/ukdmc/Radioactivity/Th_chain/Thbin.jp...

http://www.bridgeportinstruments.com/literature/isotopes/thn...

http://hepwww.rl.ac.uk/ukdmc/Radioactivity/Th_chain/Thgamma....

So the monazite gives off radiation - gammas - that can make it through lead foil, but at a low rate and possibly not well stopped in the thin emulsion.

YT2095 - 11-1-2008 at 02:09

well it has been suggested that I try Film rather than the papers, the Logic being that it takes several seconds to expose the paper but fractions of a second to expose film.
(it will also give the advantage of making Positives of these later).

so I May be able to cut down the exposure time to just a day, but being a bit of a Newb with photography, I have no idea how True this is?

Logically it would seem to make sense, but I can imagine that I may lose resolution a little as there won`t be as many "Pixels" in the area (or whatever they`re called).

btw, Great post Not_Important! ;)

[Edited on 11-1-2008 by YT2095]