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Tim Gray
02-06-2009, 08:16 PM
I'm making my way through Haist right now and I think I've read enough to actually formulate a question now. Haha. Is two electron sensitization a process by where you can make a latent image site with two as opposed to three photoelectrons? Or is it something else? Am I right in saying that to make a development site, you need at least three photons?

I find it fascinating that film was/is such a huge industry and yet we don't actually know the mechanics of how the latent image is actually formed. Has more work been done in this area that postdates Haist? Or is it still up in the air? I guess if we don't know exactly how it works by now, we probably never will, given the decline of film.

Photo Engineer
02-06-2009, 08:33 PM
Basically, you are correct. Also, the method was unknown at the time the books (Haist) were written. It uses a penta cyano osmate complex with a dye to achieve this.

And no, no one will ever know the full story AFAIK. We are watching a tragedy unfold and most people do not care.

PE

Tim Gray
02-06-2009, 08:38 PM
Thanks about the 2 electron business. I used to think we were going from 1 -> 2, not 3 -> 2. I guess I was thinking that effective speed was doubled, so electron sensitization doubled. haha.

That irks me about the latent image thing. If it I grew up 40 years ago, I think I would have been tried to do research in photo. I feel like I've arrived to the party late.

AgX
02-06-2009, 08:52 PM
Tim,

things are even more complex: gaining a stable nucleus does not necessarily mean that is developable.

Those last concepts in enhancing sensitivity were all based on scavenging a hole while at the same time yielding a 2nd electron (next to that photolytic one) from a coupled reaction.
Concepts varied in efficiency and practicability.

Anyway, they relate to the efficiency by which use is made of an absorbed photon, not to the number of electrons needed for a nucleus.

keithwms
02-06-2009, 09:04 PM
That irks me about the latent image thing. If it I grew up 40 years ago, I think I would have been tried to do research in photo. I feel like I've arrived to the party late.

Before he passed, I got to know Jack Mitchell (just look up "latent image" in wikipedia) and he was really upset at how quickly the research stagnated. He expressed extreme dismay with Kodak and told me that if I wanted to carry on with his work I should move to Japan. Very irritated, Jack was! I later realized that he'd had some sort of bashing of heads with someone at Kodak (I don't recall the name) on the subject of alternative sensitization schemes. According to Jack, there was/is all sorts of room for improvement, but the research was simply stopped. The only thing that put a smile on his face was that I told him I was still happily using panatomic-x!

Jack had late-stage Alzheimer's, and our discussions were extremely scattered, so I had trouble piecing his stories together with concrete dates, but my general impression was that according to him, circa 1990, research at Kodak began to stumble and there was no real interest there in "saving" film at the highest levels of the company.

B&Wpositive
02-06-2009, 09:12 PM
Basically, you are correct. Also, the method was unknown at the time the books (Haist) were written. It uses a penta cyano osmate complex with a dye to achieve this.

And no, no one will ever know the full story AFAIK. We are watching a tragedy unfold and most people do not care.

PE


Wow! I had no idea that this process is still largely an unknown quantity. I guess only quantum electrochemistry has a chance at answering the question of what exactly happens when light hits film, right?

AgX
02-06-2009, 09:16 PM
We ain't know nothing yet.

Tim Gray
02-06-2009, 09:20 PM
I would love to do research in this, but it's a bit outside my field. Probably be hard to get grant money too.

keithwms
02-06-2009, 09:20 PM
B&Wpositive, according to Jack, there was a lot of solid-state physics involved. Of course, one has to consider grain geometry and the placement of sensitizers along the grains etc. And the basic picture you can have in your head is that a photon comes in, generates an exciton (electron-hole pair). The electron goes off and does its thing. But in nanoparticles there is extremely strong exciton binding energy and what the hole does most certainly does affect what the electron does. Their migration is likely correlated, so... Jack's big contribution was basically "don't forget the hole!" And I suppose he had the idea that you want to prevent recombination of the electron and hole. That's my 30 sec explanation ;)

And yes, Tim, it is very hard to get grant money for this ;) especially now. But I gathered form Jack that even in "the day" money was not plentiful and he got money from his father to support much of his work. His father got money from the bright idea of using a camera to reproduce maps, rather than redrawing them by hand.

Tim Gray
02-06-2009, 09:29 PM
Haha. Well in that case I'll stick to the DOE and NSF :D

keithwms
02-06-2009, 09:39 PM
DOE and NSF haven't been good to me of late, last little trickle of funding I got was DARPA, they still have some money.. But not for this kind of thing!

Getting funding for science right now is like milking a petrified cow.

Tim Gray
02-06-2009, 09:42 PM
Yeah, its a bit tough. Fortunately my group is in the beginning of one grant cycle (the one that pays my paycheck) and the other one comes up this year, but shouldn't be too bad. We'll see...

Photo Engineer
02-06-2009, 11:02 PM
Wow! I had no idea that this process is still largely an unknown quantity. I guess only quantum electrochemistry has a chance at answering the question of what exactly happens when light hits film, right?

You misunderstood.

It was not discovered when Grant wrote his book. That is all.

PE

Photo Engineer
02-07-2009, 10:05 AM
Keith;

After reading over the posts again and the Wikipedia article on latent image, I would have to say that much more is known inside of Kodak than has been published, and the same is true of Fuji. In addition, fundamental R&D was going strong in the period from 1990 - 2000. Howard James and Tadeki Tani often met in exchange visits and I had the opportunity to attend some of those and ones between Tani and Gilman as well.

I am not a physical chemist, but I know that what they talk about within KRL is a far cry from what they publish!

PE

B&Wpositive
02-07-2009, 11:22 AM
So there are places where the information is known and utilized, but a lot of it is still generally unknown outside of the industry? Makes sense.

I hope there are a few university professors who study this sort of thing, because once most of the photographic research people no longer research it, there has to be someone to take over the knowledge base, even if just to keep the information on file for the future so it doesen't get forgotten.

keithwms
02-07-2009, 12:10 PM
Keith;

After reading over the posts again and the Wikipedia article on latent image, I would have to say that much more is known inside of Kodak than has been published, and the same is true of Fuji. In addition, fundamental R&D was going strong in the period from 1990 - 2000. Howard James and Tadeki Tani often met in exchange visits and I had the opportunity to attend some of those and ones between Tani and Gilman as well.

I am not a physical chemist, but I know that what they talk about within KRL is a far cry from what they publish!

PE

That's true, I agree. One of Jack's principal complaints was that certain people at Kodak knew very well that there are far greater possibilities... but there was no action on what was known.

Anyway, I am not knowledgeable at all in this area, and I was of course relying on the ramblings of a 90+ year old man with Alzheimer's. I think he started to become acutely affected in he mid 90s. He has some later review articles but at that stage he was just collecting honors and awards and traveling around Japan. I doubt Jack himself was active past 1995 or so.

Photo Engineer
02-07-2009, 12:21 PM
Keith;

I could name at least 5 people in the 90s doing long range fundamental research. Some of this resulted in the 2 electron sensitization and others resulted in some unique viewpoints of stabilzing latent images and improving their capture. The result of this is that todays films have far less reciprocity failure and are subject to far less solarization with overexposure.

They also keep better. You understand that keeping is a function of the heat treatment with sulfur + gold, but it continues in your hot glove compartment. Well, they pretty much know how to quench that nowdays.

So, the fundamental work was ongoing, just not public! Same with Fuji.

And yes, these are considered trade secrets if not patented.

PE

Tim Gray
02-07-2009, 12:23 PM
I'm still sad that that heat developed ISO 25,000 film was never circulated. I would have LOVED to try that.

keithwms
02-07-2009, 12:30 PM
Ron, why were these products not brought forward? Was it simply that it'd cost a lot to bring them to market?

Photo Engineer
02-07-2009, 02:24 PM
Keith;

I can give you a short list.

Kodachrome 400 with T-grain technology. No interest, cancelled ~1990.

Iridium doping, difficult due to decomposition of iridium salt/complex. It took years to perfect a method to stabilze it.

Osmium doping, 2 electron sensitization, emulsions went bad too quickly and new methods of stabilization had to be developed. It had to be optimized for each film emulsion.

25,000 speed film, IDK, but they expressed no interest to go beyond the initial phases of demonstration.

3000 speed instant died due to lawsuit.

CD-6 plans died due to lawsuit.

Formate died due to - it didn't work out at all.

Selenium died as it was toxic and hard to get to work.

Tellurium died due to toxicity, but is in use by Fuji.

What did go to market after a lot of R&D.

Iridium, Osmium, T-grains, UF washing, automated making, scalable mixing - these are things not seen and are very tightly patented, controlled and considered manufacturing secrets. For the first 15 years at Kodak, I got about 1 patent/year, but after I went into emulsion work, nothing of my work was published outside of the company although I published about 100 internal reports during that time. As for the 15 patents, there were nearly 100 reports and 100 Invention Reports internal that never got published. So, there is an average ratio.

Since each project took 1 - 5 years with anywhere from 2 to 9 researchers and that many or more support people such as coaters, the projects cost in the millions of dollars.

PE