Raman Spectroscopy

In the Keanu Reeves movie Siberia, Keen-o uses a magic box to tell real diamonds from fake ones. The fake diamonds aren't really fake, they are just as real as the real diamonds. The difference is the fake ones were manufactured while the real ones were dug out of the ground. I think the difference the machine is looking for is the presence of nitrogen - real diamonds have it but artificial ones don't. After rooting around for a bit I found that Raman Scattering is what the magic box uses to detect the presence or absence of nitrogen.

 
Raman spectroscopy has been around for awhile:

The Raman effect was named after one of its discoverers, the Indian scientist C. V. Raman, who observed the effect in organic liquids in 1928 . . . Raman won the Nobel Prize in Physics in 1930 for this discovery. 

In the beginning it was very difficult to observe the phenomena. Lasers have made it much more practical. Let's let YouTube show us how.


Intro to DIY Raman Spectroscopy
Applied Science

Not the smoothest exposition, but he covers all the major points.


Homemade Raman Spectrometer: Diamond
toc1955

This one is so short that you won't have time to read the text. Remember the space bar is your friend. It's here because he has some good graphs of the results.


Basics and principle of Raman Spectroscopy | Learn under 5 min | Stokes and Anti-Stokes | AI 09
Practical Ninjas

Mr. Ninja is not a native English speaker. In this case subtitles are your friend.

Lastly, if you want one of these magic boxes, you can buy one from Stellar Net though it will cost you a pretty penny.

StellarCASE-Raman - Portable Raman System for Material Identification | StellarNet, Inc.

King Tut

Nickel, sulfur, and chlorine elemental distribution maps of one side of King Tut's dagger, analyzed with portable XRF spectroscopy.

Got onto this from a YouTube video short. Another example of a special kind of spectrometry. This one is X-ray fluorescence. Previous posts about spectroscopy. Spectroscopy and spectrometry are two different words. ATA Scientific Instruments explains them both. The difference might matter to some people, but to me it's more like the difference between either and either.

Previous post about King Tut.

Electrons

I'm reading Andy Weir's Project Hail Mary and he's messing about with light and spectroscopy and I was just reading about that for my post about the Keanu Reeves movie Siberia and all this got me to thinking about electrons.

I think the problem I have is that there are two forms of heat and I don't understand how they are connected. There is the gross form of heat where atoms vibrate. As I recall, all atoms are vibrating all the time. The higher the temperature, the stronger the vibration. The only time they stop vibrating is when they are cooled all the way down to absolute zero. No vibration, no motion, no temperature. 

Atoms at peace don't vibrate much, they are content with their lot, locked into fixed relationships with their neighbors. Everybody minds their own business, but they all talk to each other, neighborly like. No hot-rodders tearing through our town, least not since that Packer kid's girl dumped him.

Heat things up and the vibrations get stronger and all those friendly, neighborly bonds aren't quite so strong, or maybe they've just move out of reach. It's like our fence has been doubled and our lots are drifting apart.

But then there's the other kind of heat where the electrons get excited. A photon comes blasting in from out of town, hits one of our happy little atoms and one of the electrons gets boosted to a higher orbit. Okay, it's not an orbit, it's a higher state, you know, closer to nirvana. But then, after a while, the electron returns to its previous, normal state and in the process emits a photon. 

Now we come to the crux of the matter - what is 'after a while'? What determines when that electron decides to return to its previous, lower state? Does it take a while to figure our that nirvana isn't all it's cracked up to be? Yeah, somethin's goin' on that I do not understand.

P.S. Andy Weir also wrote The Martian, which got made into a movie, and Artemis, about a moon base. The movie was pretty great. Artemis was entertaining.

The Diamond Age

The Diamond Age (as in The Bronze Age or The Iron Age) might have not quite arrived, but it's getting closer. We now have a couple of different methods for making synthetic diamonds and they work well enough that they are economically viable, i.e. they can make gemstone size diamonds and are undercutting the natural diamond producers like DeBeers.

I remember hearing about some guys trying to make diamonds a while back. They were having some success using washing-machine size machines that focused enormous pressure on a tiny little sample. That was ten years ago or so.

The Diamond Age is also the title of a science fiction novel by Neal Stephenson. One of the premises of that story is that man has learned to make diamonds and it has opened whole new venues of technological progress. Society as a whole still sucks, but what else is new?

I'm not sure how I got started on this, but when I started looking I wasn't finding much, well, except for a bunch of ads for engagement rings. But eventually I found some bits and pieces. Here are some videos give a pretty good overview of what's been going on.


Growing Synthetic Diamonds

synthetic diamond factory

These lab-grown diamonds are identical to natural ones

How To Make A Diamond - Bang Goes the Theory - BBC O
I also remember watching a video where a guy made diamond from pencil lead using a microwave oven, but I can't find it now, so maybe I just imagined it. If so, I've got a really good imagination because I remember it clearly. In any case he turned a ceramic coffee mug upside down and used the depression in the bottom as a crucible. He laid a couple of leads from a mechanical pencil there and added a couple of drops of oil (mineral? vegetable? my memory is fuzzy on this point). He set another coffee mug on top, this one right side up, so the graphite and oil are semi-contained, and then he fired up the microwave and ran it for I don't know how long. I don't recall what method he used to verify that his experiment worked, but if it did, the crystals were very small. Really bugs me that I cannot find this video.

The older HPHT (high pressure, high temperature) method is still in use and has grown considerably:

A synthetic diamond factory in China

And grown some more:

HENAN GAINS CO., LTD, located in Zhengzhou China

China is producing quantities of gemstone quality synthetic diamonds and shipping them to India where they are cut and made into jewelry.

Considerable effort has also been expended in finding ways to determine whether a diamond is synthetic or natural. One way was to laser engrave some kind of a miniature marking on the edge. Another uses spectroscopy. Natural diamonds usually include a bit of nitrogen and synthetic diamonds don't.