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Anybody played with elemental selenium as a target?

Spudinator

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Hello and happy Easter everybody. So I was going through my element collection today cataloguing what I had left to get (two left, yes! Thorium and Polonium), when I chanced upon a lovely piece of pure Selenium, a semiconductor which has been largely phased out of commercial use due to better performance of other elements such as Silicon, but is still used in some solar panels. On a whim I pulled it out of it's container to look at it, and after a moment wondered what 5.1 watts of 470nm light would do to it when focused to a point the size of a needle.

I was surprised, to say the least, by how much material it was vaporizing the instant the beam touched the highly reflective metalloid. The stuff looks like polished hematite, you would think it would mostly shrug it off, but no. I could drill a hole through the 28 gram sample if I wanted to vaporize a gram or two into the air, but I don't. I also tested other wavelengths, including a relatively weak 165mW 492nm Sanwu pocket (waaaaaay overspec 100mW, love Sanwu), and they all rapidly vaporize the Selenium as well, though I don't have an IR laser so that's a mystery. Apparently Selenium's electrical conductivity increases on exposure to light and must absorb a lot of energy if it's used for solar panels so I guess it makes sense but I'm still blown away by how rapidly it burned off. It's as fast and aggressive a burn as any material I've tested before, black plastics or paper included, the plume of material shoots out about 3" if properly focused.

Has anybody else done anything like this, such as firing lasers at random pure elements? If you haven't burned Selenium and enjoy burning stuff, you might want to pick up a chunk or two on ebay and test this theory out yourself, its pretty cool. I don't suggest doing this stuff indoors though as it has a sulfur/rotten horseradish smell, found that out the hard way. Probably shouldn't breath the direct fumes either, lungs don't require vaporized semiconductors for longevity of use...

I'll shoot a video and post it to YouTube sometime soon and give you an idea of how much matter is removed. It's also cool because the selenium melts at only 428 degrees, but is still very soft and pliable at much lower temperatures after being heated (key part there, if it cools you have to bring it all the way up to melting again to make it pliable again). I melted some in a small stainless dish and poured out a small glob which was still connected to the cup by a thin strand (the stuff is like maple syrup when melted) and as it cooled I slowly lifted the cup upward which drew a very consistently thin strand about .015" at 6 feet long which I was able to spool up like a peice of wire. It really is a very cool element to play with, I'm surprised there are no videos on YouTube about it other than Periodic Videos.
 
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BowtieGuy

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A belated Happy Easter to you, Spudinator; I've never seen how selenium reacts to a laser beam, so a video would be interesting, be sure and let us know if you make one. :)
I agree with you, those created vapors should definitely be avoided!
 

paul1598419

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I remember the smell of selenium diodes used back in the 1970s for high voltage rectifiers. It was awful. It is not something I would try to recreate.
 

Spudinator

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Thanks BowtieGuy. I finally got around to making a quick clip of me burning a smaller chip of Selenium I had, nearly made it through the whole peice in a couple seconds.


I don't blame you Paul, the stuff reeks.
 

LSRFAQ

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Please tell me you did not breath in the vapor from one of the most cytotoxic , mutagenic, cancer causing bulk materials on the planet?
Yeah, we need trace amounts of it to live. But what long term exposure does to your lungs, skin, teeth, kidney, nervous system is VERY bad.

Yeah, the fumes are a beautiful reddish violet color, but long term effects include bronchial damage and permanently discolored skin..


DONT BREATHE METAL VAPORS or METAL OXIDE DUST. JUST DONT.

Steve
 
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MrBland

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I wouldn't mind seeing a video, since I won't be damaging lungs myself lol. Probably would make a nice pic though.

If someone does just remember to use proper safety precautions.
 

Spudinator

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Ohh hell no, I held my breath through the whole thing and left the area afterward with windows open. Probably should use a respirator but mine is at work currently. At least the smell doesn't linger for too long. I've heard more than once how toxic Selenium can be but all the people raving about supplementing it for health benefits far outweighs those voices, as with most things these days (like the derps who drink turpentine). At what levels does it become toxic?

Edit: Just noticed in the video the laser did melt through, but the molten material kept filling the hole back up due to it's insane surface tension, cool.

Mr Bland I made a video and linked it to my previous post, is it not showing up? It's YouTube's embedded player link if that makes a difference.
 
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