Diffraction of c60. seeking description of experiment.


by foobar
Tags: description, diffraction, experiment, seeking
foobar
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#1
May9-12, 10:22 AM
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I find this hard to believe.

I do not have access to the Nature article below.But would like to know more detail of what was done or see a copy of the Nature article.

Wikipedia: "In 1999, the diffraction of C60 fullerenes by researchers from the University of Vienna was reported" :

"Wave–particle duality of C60". Nature 401 (6754): 680–682. Bibcode 1999Natur.401..680A. doi:10.1038/44348. PMID 18494170.

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DrChinese
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#2
May9-12, 10:43 AM
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Quote Quote by foobar View Post
I find this hard to believe.

I do not have access to the Nature article below.But would like to know more detail of what was done or see a copy of the Nature article.

Wikipedia: "In 1999, the diffraction of C60 fullerenes by researchers from the University of Vienna was reported" :

"Wave–particle duality of C60". Nature 401 (6754): 680–682. Bibcode 1999Natur.401..680A. doi:10.1038/44348. PMID 18494170.

TIA
Try this:

http://www.julianvossandreae.com/Wor...c60article.pdf
foobar
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#3
May9-12, 01:38 PM
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DrChinese
Thanks for that.
foobar


Would appreciate if anyone could say how credible is this claim of diffraction of C60.
Could their diffraction pattern be from some other innocent cause?

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May9-12, 02:21 PM
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Diffraction of c60. seeking description of experiment.


Quote Quote by foobar View Post
DrChinese
Thanks for that.
foobar


Would appreciate if anyone could say how credible is this claim of diffraction of C60.
Could their diffraction pattern be from some other innocent cause?
Additional info from this well respected team:

http://www.univie.ac.at/qfp/research...c60/index.html
http://www.univie.ac.at/qfp/research...lightwave.html

They compare theory and experiment, which agree fairly well. Is there a particular reason you are questioning this experiment?
Seaumas
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#5
May10-12, 02:17 AM
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I don't know. Did you read Eric S. Reiter's 2008 paper, "Partical Violation Spectrometry"? He makes some heavy claims akin to turning the world on its head. I like that kind of chutzpah. Is this why you inquired?
f95toli
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May10-12, 05:45 AM
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Quote Quote by foobar View Post
DrChinese
Thanks for that.
foobar


Would appreciate if anyone could say how credible is this claim of diffraction of C60.
Could their diffraction pattern be from some other innocent cause?
There have been many demonstrations of diffraction of "heavy" particles. A very recent one is

http://www.nature.com/nnano/journal/...o.2012.34.html

The heaviest particle they use has 114 atoms in it...
(also, you can watch the movie if you want ).
billschnieder
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#7
May10-12, 04:56 PM
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What about diffraction of macro droplets with millions of atoms each

http://prl.aps.org/abstract/PRL/v97/i15/e154101
http://www.youtube.com/watch?v=GHHaDWEWtQE
foobar
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#8
May11-12, 05:46 AM
P: 11
Thanks for the info and comments all.

I am skeptical of claims that atom or molecules just split in two parts one goes through
one slit another thro the second and they recombine in an interference pattern, where the particle is supposed to be described by an amplitude psi. To seriously believe that some C nucliei could go thro one slit and others thro the second and recombine into C60. I need a lot more convincing.

Any such theory just needs a lot more clarity and proof before I would accept it.

The Couder link thing is very interesting.
And here is a nice article about it: web.mit.edu/newsoffice/2010/quantum-mechanics-1020.html

This would point to some kind of pilot wave on which matter waves ride. This was de Broglies idea originally but not accepted generally.
Under some theory like this C60 would not split in two but go thro one slit and the wave thro both.A lot more credible.

The c60 interference pattern is probably genuine but it is the explanation for it I doubt.

foobar
jtbell
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#9
May11-12, 08:04 AM
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Quote Quote by foobar View Post
I am skeptical of claims that atom or molecules just split in two parts one goes through one slit another thro the second and they recombine in an interference pattern, where the particle is supposed to be described by an amplitude psi. To seriously believe that some C nucliei could go thro one slit and others thro the second and recombine into C60. I need a lot more convincing.
The mathematical machinery of QM doesn't actually say anything about what is "really happening" to the C60 molecule, or whatever other particle that is being used in the double-slit experiment, before it reaches the detector or viewing screen. This is the province of the various interpretations of QM, about which people argue a lot because there is little experimental evidence that could help us distinguish them. In the Bohmian interpretation, for example, the particle does explicitly go through one slit or the other, without "dividing."
foobar
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#10
May11-12, 08:13 AM
P: 11
Seamus

No I had not read that. this is the article I think. unquantum.net/particleviolationspectroscopy.pdf

foobar.
DrChinese
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#11
May11-12, 09:10 AM
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Quote Quote by foobar View Post
The c60 interference pattern is probably genuine but it is the explanation for it I doubt.
OK, the pattern does result and this is an experiment which has been replicated. Not much to question there.

As to the explanation, I think you have it backwards. In the theory, the wave function goes through both and that is it. And the theory correctly predicts what is observed. So there really isn't much to doubt there either. Further, theory says that if you can determine which slit something goes through, there is no interference. Which is also observed.

The only question is whether there is a *deeper* explanation. No one knows yet. However, the thing about the molecule going through one slit or both or splitting or whatever is not actually part of the theory. That is part of an interpretation, as jtbell points out.
foobar
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#12
May11-12, 12:40 PM
P: 11
OK I was hasty in doubting the results. As I said the pattern is probably a diffraction pattern.

I must disagree with your other comments. My point was and is a reasonable one to make.

Wave/particle duality is part of QM.

en.wikipedia.org/wiki/Matter_wave
quote from wikipedia:
"In quantum mechanics, the concept of matter waves or de Broglie waves reflects the wave–particle duality of matter."

quotes from the C60 Nature article:
"Here we report the observation of de Broglie wave
interference of C60 molecules by diffraction at a material absorption grating"
"The minima
between zeroth and first orders are well developed, and are due to
destructive interference of C60 de Broglie waves passing through
neighbouring slits of the grating."

I do not believe this is what is happening.

I think it more likely that something like the Bohm theory / interpretation might be happening, or some other possibility.

Also the de Bohm theory is very much not a standard interpretation.And in fact looks more like a different theory rather than an interpretation, with a pilot wave AND guiding wave.
Copenhagen would be standard AFAIK.
DrChinese
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#13
May11-12, 02:22 PM
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Quote Quote by foobar View Post
quotes from the C60 Nature article:
"Here we report the observation of de Broglie wave
interference of C60 molecules by diffraction at a material absorption grating"
"The minima between zeroth and first orders are well developed, and are due to
destructive interference of C60 de Broglie waves passing through
neighbouring slits of the grating."

I do not believe this is what is happening.

I think it more likely that something like the Bohm theory / interpretation might be happening, or some other possibility.

Also the de Bohm theory is very much not a standard interpretation.And in fact looks more like a different theory rather than an interpretation, with a pilot wave AND guiding wave.
Copenhagen would be standard AFAIK.
You are free to believe whatever you like.

It is an axiom of Bohmian Mechanics that it produces the same predictions as standard QM. So you can call that whatever you like. Similarly, diffraction experiments are intended to highlight the wave-like nature of particles. Whether the waves are "real" or they are "pilot" waves or whatever does not change things. The behavior itself is quite real.
foobar
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#14
May11-12, 03:01 PM
P: 11
I made no statement about the predictions of QM being different from Bohmian mechanics sir.
I am only interested in the physics of what is happening.
and have no interest in a semantic or pedantic discussion.


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