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Complete Measurement of Molecular Breakup
Suidae writes "PhysicsWeb is reporting that physicists have made a 'complete' measurement of the break-up of a molecule for the first time. Reinhard Dörner of the University of Frankfurt and co-workers in Germany, the US, Australia and Spain recorded the two electrons and two nuclei that were released when a single photon split a molecule of deuterium into its basic components. The experiment could lead to a better understanding of many physical and chemical processes through improved knowledge of the quantum dynamics of many-particle systems."
Deuterium is an isotope of hydrogen, not a molecule.
FP BTW.
Stop fucking quoting me, damn it! -- Larry Wall in <200405106932.MAA00246@wall.org>
But curiously, drinking deuterated water is apparently poisonous.
This is because the chemical behaviors of deuterium and light hydrogen are slightly different.
You can think of the electron and nucleus co-orbiting about a common centre of mass, rather than the electron orbiting while the nucleus remains fixed. Where the point is depends on the ratio of the masses of the electron and the nucleus (about 2000:1 for light hydrogen, and about 4000:1 for deuterium). The different orbit radius (for any given energy) for each case means that the energy level at which the orbit circumference is an integer number of electron wavelengths will be different for deuterium and light hydrogen.
This means that the energy structure of the electron shells is slightly different, which means that they will behave slightly differently chemically. This fact is exploited in some of the methods of isolating heavy hydrogen from light hydrogen (electrolysis method, as the reduction potential is different, and the more common chemical method involving forming hydrogen sulphide, as the rates of reaction are different).
In the case of ingestion, deuterium's chemical behavior is similar enough to that of hydrogen that it gets incorporated into chemicals and otherwise interacted with as hydrogen would be, but different enough that it mucks up some of these reactions. Result, poisoning, much as you get from heavy metals displacing their chemical analogues (though less so, because D and H are a lot more similar, and your body cycles hydrogen through itself pretty quickly, while metals tend to accumulate).
As far as hydrogen isotopes go, though, tritium is the main concern. It's a beta emitter, and is formed in water-cooled reactors (especially the heavy-water-moderated reactors Canada uses, as only one transmutation step is required instead of two). It's a very low-energy emitter, but if ingested, will still cause problems. It's less nasty than most contaminents, though, as hydrogen gets cycled through the body very quickly, and tritium has a half-life of about a decade (short enough to disappear within a lifetime, long enough that it cycles out of the body without depositing much of its radiation dose).
Deuterium is mildly chemically toxic, but is not radioactive.
Okay? Get it? There's nothing confusing about it; nothing weird. Two deuterium atoms come together to form a molecule. Each nucleus has a positive charge. They're breaking up a molecule, not an atom or nucleus.
Why do you think this has the worst writeup ever?
/. standards.
A photon is used to break apart a molecule. Measurments are made; stuff might be learnt.
It's actually a pretty good summary, especally by
Now do you believe I RTFA?
Hydrogen atom (thus, I think, molecules...) is very well-studied theoretically. Gosh, they don't just stop at calculating different energy levels due to Coulomb force. At third-year level of undergraduate physics classes, they already calculate fine-structure splitting, hyperfine splitting, and even Zeeman splitting, in presense of a magnetic field. At that level, the theory is getting so accurate, and the energy level splitting becomes so small that if you want to fit a photon of right energy between the energy levels, you have to go down to the frequency of radio waves. It's not like we need experimental results (as in the case of more complicated atoms) because you can't solve (or approximate very closely) for the energy levels of the atom.
Since deuterium is practically identical to hydrogen, unless you want to study the nucleus itself (I mean... it's two fermions, so something must be different, even though they are not identical particles), what's the point of publishing results of an experiment like this? This sounds not much more sophisticated (or important) than the experiments done in advanced physics lab (er... optical pumping, Rutherford scattering, NMR, etc. etc.).
It would be a totally different matter if they found something that contradicted predictions of an established theory...but, did they?