Deuterium & Democritus

Deuterium & Democritus

(Originally posted July 17, 2016 on Blogger)

What would the Institute of Physics and Technology have to do with ancient Greek history? I wasn't sure whether to write this blog under my Science & Nature category, or Culture & History. Since I've yet to write any blogs under the latter, I've thus chosen Culture & History for this blog entry.

The Calydonian hunt.

The Calydonian hunt.

Ah, the amphora. Artform in both ceramics and paint. Beautiful vases created by ancient hands often covered in captivating artwork depicting scenes that spark the imagination. This amphora likely depicts the hunt of the Calydonian boar. Artemis (Diana in Roman times)--who I believe was a pre-Greek goddess--supposedly sent the enormous boar into Calydonia to destroy it in order to exact revenge for the king's apparent memory lapse at the harvest festival, during which he was supposed to offer a sacrifice to the goddess. A likely story. Hmmm... I have my own hypothesis which (I like to think) makes much more sense... alas, I cannot reveal what I believe as it is being incorporated into an epic I hope to finish before I'm dead..

During the Greek Classical period (circa 5th-4th centuries BCE), there were generally three types of painting styles on amphoras; red figure, white background, and black figure... the latter of which the Etruscans had their own industry oriented on Greek models. While the amphoras themselves were sculpted by the hands of seasoned pros, the lids were, apparently, sometimes made en masse by children. Evidence of such has been uncovered as recently as this past summer when submerged amphoras were brought to the sea surface off the coast of present-day Italy... children's fingerprints were seen on some of the lids.

I suppose the fingerprints could have been from little Aleksander being a troublemaker! But evidence seems to suggest some child labor going on. Tsk tsk!

So where does the physics department at a prestigious institute in Russia come in with all this?

In a paper published about 2 weeks ago (at the time of this writing), scientists at the Moscow Institute of Physics and Technology successfully used mass spectrometry to look "into" an ancient Greek amphora that dates back to around 2,500 years before present... around the start of the Classical period. Scientists were able to come up with this age precisely because of their ingenious use of mass spectrometry.

What is mass spectrometry, and what would Democritus think of it?

Let's start with Democritus, the laughing philosopher who put as much credence into the exploration of the mind, as he did in the importance of cheerfulness; something we can all take note of in our own lives yes? Long before Dalton, Rutherford, Thomson and his "plum pudding" atomic model, Bohr, and others... there was Democritus. For it is he who first truly elaborated upon the idea of all things in the world being composed of smaller things; atomos. And though other ancient thinkers had imagined the idea of all things being composed of smaller things, it was Democritus who organized and espoused his thoughts on the matter (pun... get it? Matter? Don't worry, I'm here all night).

An Italian-made bust of Democritus from the 1700s

An Italian-made bust of Democritus from the 1700s

Democritus is considered by many, to this day, to be the "father of modern science", and set the stage for atomic theory. Believe it or not, his brilliance was largely ignored by Athenians of his time, and Plato thought Democritus' writings should be burned! A bit ironic coming from the man who established the first institute of higher learning in the Western world (of which Aristotle attended), I'd say. Jealous much Plato? Oddly, only fragments of Democritus' writings have survived... Plato! Shame on you! What would your teacher, Socrates say!?

Here's food for thought... Plato once said, "We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light." Given the fact that from modern atomic theory we know that photons (light) are released when electrons drop to lower energy levels (clouds), I'd say that's one heck of an ironic statement by Plato! Only took 2,500 years to see that irony work itself out.

Ok, enough Plato bashing.. he was far more brilliant than I'll ever be, and though his student--who would go on to tutor Alexander of Macedon--was a bit of a xenophobe, I'd say their contributions to Western philosophy are unparalleled. ...though xenophobia seems to permeate portions of Western culture still... Ok, Ok, I am shutting up now! Back to Democritus' idea of smaller things making up bigger things. Atomos, the Greek word for atoms: indestructible, indivisible little things that make up everything(s).

He attributed these atoms' shapes to whatever it was that they combined together to create. Sharp, angular atoms would create such things as salt. Smooth, rounded ones formed together to make water, for example. As it turns out, mass dictates atomic classification (on the periodic table), and mass is what scientists in Russia looked at to date an ancient amphora. Well, to be more precise, the mass-to-charge ratio is what they looked at. So what is this mass:charge ration I speak of?

Look, I'll be the first to say I know nothing! But we all know in quantum physics that something can come from nothing! So let's delve into the what Mass Spectrometry is!

As it turns out, the atom is comprised of nucleons (neutrons and protons) and electrons. These are themselves composed of yet even smaller particles which I kind of explain in another blog over in the Science & Nature category. But for now, let's concentrate only on the basic components of an atom. Neutrons have no charge, protons have a positive charge, and electrons have a negative charge. I'll get to what they weigh later, as that's important with regard to mass spectrometry. Atoms like to remain neutral insofar as charge is concerned. And they do this by maintaining, or trying to maintain, an equal number of protons and electrons. However, there are instances where electrons are gained in excess of the number of protons, or electrons are lost in deficit of protons. The former (gain of electrons) results in a net negative charge. If electrons are lost such that more protons exist, the atom is left with a net positive charge, since there are more positives (protons) than negatives (electrons). When atoms lose their neutral charge in either of these cases, they become what are called ions.

There are two flavors of ions. Cations and anions. Cations are positively charged ions. Easy to remember, because cats have paws... paws...itive. Anions are the negatively-charged ions.

In mass spectrometry, molecules of a chemical species (molecules of the same type) are ionized. That is to say, they are given a charge. How this is done is through electron impact ionization. Within the mass spectrometer, high-energy electrons hit a stream of gas-phase molecules. When this occurs, a few things can happen to those molecules. One, they can have an electron knocked out of them, resulting in radical cations. Radical as in unpaired electrons, not like totally awesome electrons... although, electrons are pretty awesome. Sometimes high-energy electrons hit a molecule and radical cations can fragment into different "sized" fragments. Sometimes the larger fragments get the charge, and sometimes smaller fragments end  up with the charge. I spared you the details only to iterate that what results, overall, is a bunch of ions of different masses.

Next comes the mass analyses, which requires mass filtration.. in other words, scientists have to now separate out these different masses of ions such that smaller, intermediate, and larger masses are grouped together respectively. The spectrometer does this by focusing all of these different-sized ions into a beam and it directs this beam into a vacuum chamber within which there is a magnetic field. A magnetic field that can be manipulated to be stronger or weaker. I'll get to why it needs to be manipulat"able" in a second...

This beam of differently sized ions would travel straight if no magnetic field was present, but with a magnetic field applied, the ions experience a force which curves their otherwise straight paths such that they "fall out" at different distances. A point charge (ion) at a given velocity (speed and direction) when passed through a magnetic field will experience a force whose influence is proportional to the mass of that particle.

F=MA, where force equals mass times acceleration. If we rearrange this equation, we find that acceleration equals force divided by mass. Force (the magnetic field) is constant, but it's the mass of these different ions that differs from particle to particle.. as such, the acceleration for each is different depending on their respective masses. In other words, lighter ions are deflected more than the heavier bastards. Thus, the magnetic field separates the beam of ions such that small guys fall out first, intermediate gals fall out second, and the large folks fall out last, in terms of distance from the entry point of the ion beam. Oh geez, I hope I'm explaining this ok.

Important thing to note is that now we have the ions separated out, and we can move on to the electron multiplier detection system. The electron multiplier detection part, yes it's a real thing, is a vacuum chamber with dynodes.

Dynodes are a special material that, when "hit" by ions, eject an electron. A dynode, you could say, is an electrode (in a vacuum), and an electrode is just an electrical conductor, and an electrical conductor is just something (usually metal) that allows the flow of an electric current, and an electric current is flowing electric charge, which itself is a physical property of matter.

These dynodes are set up in a series top and bottom (or side by side depending on your perspective), and when say one electron is ejected by the first dynode when hit by an ion, that ejected electron hits the second dynode across from it and bounces off.. ahh, but it doesn't bounce off alone. It hit another dynode, therefore that dynode itself releases an electron, so now there are 2 electrons. These two electrons then hit a third dynode and each bounces off... and in so doing, release 2 more electrons from that dynode... now there are 4 electrons... those four hit the fourth dynode in the series and, you guessed it... they bounce off along with 4 more ejected electrons, so now there are 8.

The process continues as the number of electrons grows exponentially with each impact with another dynode... ultimately what results is an electrical charge measurable by the electron multiplier detection system. "Make it so."

So from all this, scientists can create a mass spectrum plot. In the case of the amphora, scientists utilized bitumen, a viscous mix of naturally-occurring hydrocarbons that was used by the ancients for everything from medicine to warfare. One heck of a spectrum if ever there was one.

The amphora they analyzed once contained bitumen, and it was discovered by Russian archeologists on the Taman Peninsula (just east of present-day Crimea along the Black Sea) accessible by ancient traders from the Mediterranean via the Dardanelles and Bosp(h)orus. Two of the most strategic places on Earth, both in ancient and modern times. The ancient Greeks routinely imported this bitumen (in amphoras) from this region. It was gas samples of this bitumen that were used in the mass analyses outlined above that gave away the amphora's great age. But what's most fascinating about the use of mass spectroscopy in dating this amphora, is that these scientists were able to utilize a much higher-resolution of analyses capable of distinguishing masses that differed in "size" by only a fraction of an electron. That's incredible, given the fact an electron's mass is nearly negligible.. and that very fact that it is nearly insignificant is how mass spectroscopy has been so successful a tool... masses of ionized molecules could still be looked at since the lost electrons really didn't alter their masses.

Such detailed analyses allowed scientists to conclude age via considerations of oxygen content in the bitumen. Bitumen, on its own, contains very little oxygen. However, bitumen from the amphora sample contained more oxygen, suggesting its exposure to air led to oxidation from ozone. The bitumen in the amphora "bears the effect prolonged oxidation" as it was written by the paper's authors. This high level of analytical chemistry really opens the door to a whole new world of potential discoveries in the realm of archeology (as well as medicine and petrochemistry).

Oxygen atoms can connect in different ways to various molecules, and how they connect dictate the chemical properties of said molecules. In order to identify these different oxygen set ups within molecules of bitumen samples, scientists used what is called the hydrogen/deuterium exchange reaction wherein hydrogen atoms are replaced by deuterium atoms (which are heavier isotopes of hydrogen)... an isotope being an atom, in this case, with an excess of neutrons than what is represented on the periodic table. Deuterium played a major role in why the nuclear detonation code named Ivy Mike had a yield far greater than expected at the time. Consequences of which were devastating... another blog perhaps.

At any rate, this deuterium shifts how things pan out on the mass spectrum chart, and revealed that ancient bitumen, as compared to a fresh sample, had extra oxygen (in the form of hydroxyls) as a result of, well, time.

I gave this a "chemistry" category rather than a "ancient history" one for several reasons, but notably because Democritus laid the foundation for such a thing as mass spectroscopy to exist, and he was likely alive and well at the time that amphora was being filled.

Thanks for reading..

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