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Rydberg Molecule Created For the First Time 127

Posted by ScuttleMonkey
from the not-around-long-enough-for-a-group-photo dept.
krou writes "The BBC is reporting that the Rydberg molecule has been formed from two atoms of rubidium. Proven in theory, this is the first time it's been created, reinforcing the fundamental quantum theories of Enrico Fermi. Chris Greene, the theoretical physicist who first predicted that the Rydberg molecules could exist, said: 'The Rydberg electron resembles a sheepdog that keeps its flock together by roaming speedily to the outermost periphery of the flock, and nudging back towards the centre any member that might begin to drift away.' It's a sheepdog with a very short life-span, however; the longest lived molecule only lasted 18 microseconds. Vera Bendkowsky, who led the research, explained how they created the molecule: 'The nuclei of the atoms have to be at the correct distance from each other for the electron fields to find each other and interact. We use an ultracold cloud of rubidium — as you cool it, the atoms in the gas move closer together. We excite the atoms to the Rydberg stage with a laser. If we have a gas at the critical density, with two atoms at the correct distance that are able to form the molecule, and we excite one to the Rydberg state, then we can form a molecule.'"
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Rydberg Molecule Created For the First Time

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  • They really are short lived. 18 seconds would be an eternity for them, apparently.

    (So, the summary here presently says "the longest lived molecule only lasted 18 seconds." whereas the article says "the longest lived Rydberg molecule survives for just 18 microseconds." Rather large difference.)

  • by mrslacker (1122161) on Friday April 24, 2009 @01:44PM (#27704303)

    > What's seven orders of magnitude between friends?

    Still out by an order of magnitude ;-)

    Anyway, "very short" (as the original article says) in the context of particle physics has often meant measurements of the order of nanoseconds (say, nuclear bomb testing measurements) or even much much small for big bang (Planck time, etc).

  • by Pearlswine (1121125) on Friday April 24, 2009 @01:54PM (#27704447)
    I bet the submitter used the micro [wikipedia.org] symbol. For some reason that symbol disappears when the story is either submitted or reaches the main page. I couldn't even copy/paste it into this comment
  • by b0ttle (1332811) on Friday April 24, 2009 @02:03PM (#27704571)
    You know we've got spectrometers nowadays.
  • Hmm... not even HTML entities work: 18 µs = 18 s = 18 s (numeric entity)

    Sorry, but the /. developers should be ashamed. They are the only site I know, that does not support UTF-8...

  • by Red Flayer (890720) on Friday April 24, 2009 @02:14PM (#27704689) Journal
    [sigh]

    NOT informative. I answered nothing not gleanable from the first few lines of the summary. It was a setup for a piss-poor attempt at Friday humor.

    I swear, sometimes I feel like I have a "Mod me up inappropriately" note taped to my back.
  • by east coast (590680) on Friday April 24, 2009 @02:34PM (#27704915)
    I swear, sometimes I feel like I have a "Mod me up inappropriately" note taped to my back.

    You must be new around here.
  • by Red Flayer (890720) on Friday April 24, 2009 @02:36PM (#27704931) Journal
    I neither care about nor need karma.

    Moderations should be made accurately, not some other fashion to game the karma system.
  • by modrzej (1450687) <m,m,modrzejewski&gmail,com> on Friday April 24, 2009 @02:40PM (#27704975)
    I've done a little research using Scholar (Phys. Rev. Lett. 85, 2458 - 2461 (2000)) and it seems that basic facts about Rydberg molecules are: 1) These are molecules made of two atoms of the same kind, enormously separated (minima of potential curves for example at about 1500 atomic units); 2) Because of extremly shallow minima of energy curve in witch they exist, they are unstable, so must be ultra cold; 3) This Rb_2 molecule despite being homonuclear, displays large dipole moment, which is unusual but predicted by theory. The experiment with rubidium described here proves that approximate quantum theory (I bet that existence of this molecule was predicted using Born-Oppenheimer approximation) is capable of describing effects subtle as this one (existence of Rb_2 Rydberg molecule is subtle one). I'm not an expert in relativistic effects, but it seems to me that this example of extremely distant separation of atoms in molecule could call for relativistic treatment: one Rb atom doesn't know of the other at once, because the information about the movement of the other can't travel faster than light. This effect may be big because of separation of these two atoms.
  • by radtea (464814) on Friday April 24, 2009 @02:51PM (#27705121)

    I RTFA, but can someone more well-versed in Physics explain what sort of implications this has?

    Not my field, but this is my sense of what's going on:

    1) Rydberg atoms have one electron in a very high state of excitation, and look like Bohr-model atoms, as the highly-excited single outer electron is so far from the rest of the atom that the combination of the inner electrons and the nuclear charge look like a point-charge, so the outer electron experiences a 1/r potential. This makes Rydberg atoms theoretically tractable with simple Bohr theory, which is always fun to play with.

    2) Rydberg molecules are make from a Rydberg atom and a normal (unexcited) atom. My guess is that the normal atom is actually inside the "orbit" of the Rydberg atom's outer electron, so it will be slightly polarized by the core field, and the resulting dipole will interact with the electron to produce the bound state. Sounds like a job for linear response theory.

    3) In general, testing systems under such extreme conditions allows us to measure precisely various properties of matter, like the fine structure constant or the electric charge or whatever. I don't know if anything like that will come out of this, but extreme systems often allow for precise tests of esoteric phenomena.

    4) Yes, this does validate quantum theory. No, it probably doesn't have much in they way of practical application, but then again, it doesn't have to.

  • by Red Flayer (890720) on Friday April 24, 2009 @03:07PM (#27705363) Journal

    its like going fishing and catching a dead baby.

    What's not to laugh about that? You can't spell slaughter without laughter.

    Reminds me of a story...

    When I was a kid, my oldest sister was a park ranger at a nearby state park with a lake. One day they get radioed by an old guy on a canoe, who said he caught a body. Sure enough, he had... and in trying to retrieve his lure, he dislodged the body from whatever was holding it under, and it floated to the surface.

    Apparently, he wasn't the first one to hook into it... just the first to retrieve it. When the puddlepolice boat motored out to him, he was furtively cutting lures our of the body and putting them in his tackle box.

    Totally irrelevant, I know.

  • by LatencyKills (1213908) on Friday April 24, 2009 @03:19PM (#27705499)
    It's been something like 20 years, but I did Rydberg atom work (using Helium atoms) back in graduate school (another student was running the vacuum rig, and I was providing the lasers for excitation and containment). As the previous poster wrote, a Rydberg atom has a single electron up in an energy state so high that it is almost unrelated to the atom which (weakly) holds it. The creation of a Rydberg molecule allows for the confirmation of a number of quantum mechanical oddities - things that were predicted by theory but couldn't be measured in a lab. It can also allow some real insight into the nature of shared bonds between atoms in a molecule and studies of weak electromagnetic forces. The Rydberg atoms themselves allowed for interactions involving electrons that were essentially at a zero kinetic energy state, teetering on the edge of a relatively enormous potential well (which is why they tend to last such a short period of time before de-excitation to some lower state).
  • by krou (1027572) on Friday April 24, 2009 @03:33PM (#27705653)
    I'd like to say "Hmmm, yes, that's exactly what I did when I submitted it", and look less of an idiot, but I'm afraid it was a mistake on my part when I submitted it. In my defence, all I can say is I have an attention span of 18 seconds ;)

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