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High-resolution images of a molecule as it breaks and reforms chemical bonds

phys.org

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Re: High-resolution images of a molecule as it breaks and reforms chemical bonds

#3

Post by csense »

ck2 wrote: post #2

Fantastic. http://cdn.physorg.com/newman/gfx/news/hires/2013/2-firsteve... Not sure how they "feel" the interactions without disturbing them but that's why they are the physicists.

> how they "feel" the interactions without disturbing them

They can't. I don't know if there are quantum complications at that scale that change this picture, but my basic idea from classical physics is that Newton's Third Law says the probe can't have a force exerted on it by the sample (action) without also simultaneously itself exerting a force on the sample (reaction).

> The single-atom moving finger of the nc-AFM

The mass of the detector particle being deflected by the fields is small compared to the mass of the molecule being measured. So a force large enough to move the probe by a lot might still be small enough to only move the sample by a little.

The bottom line is, you can't measure a sample without disturbing it, but as the ratio of probe mass to sample mass shrinks, the level of that disturbance also shrinks. In this case they're using a single atom probe to measure a large organic molecule, apparently the ratio is small enough.

> Resulting movements of the stylus are detected by a laser beam

I guess in order to engineer a system this small, you need a probe to measure the probe. Again I'm guessing the momentum of the photons from the laser that are used to measure the probe atom is small enough not to appreciably deflect the probe.

Re: High-resolution images of a molecule as it breaks and reforms chemical bonds

#5

Post by coldtea »

csense wrote: post #3
ck2 wrote: post #2

Fantastic. http://cdn.physorg.com/newman/gfx/news/hires/2013/2-firsteve... Not sure how they "feel" the interactions without disturbing them but that's why they are the physicists.

> how they "feel" the interactions without disturbing them They can't. I don't know if there are quantum complications at that scale that change this picture, but my basic idea from classical physics is that Newton's Third Law says the probe can't have a force exerted on it by the sample (action) without also simultaneously itself exerting a force on the sample (reaction). > The single-atom moving finger of the nc-AF…

>They can't. I don't know if there are quantum complications at that scale that change this picture, but my basic idea from classical physics is that Newton's Third Law says the probe can't have a force exerted on it by the sample (action) without also simultaneously itself exerting a force on the sample (reaction).

Well, that goes without saying. The question is if that "force" used to measure had any, well, measurable impact.

Re: High-resolution images of a molecule as it breaks and reforms chemical bonds

#6

Post by andy_ppp »

kumar_navneet wrote: post #4

Amazing stuff, feels really good to see that it is exactly the same as we read in textbooks.

When I looked at chemical symbols before seeing this I had always assumed them to be a sort of vague outline of what was really happening. It's amazing to think that the way chemicals bond is the same in reality as drawn in textbooks.

Re: High-resolution images of a molecule as it breaks and reforms chemical bonds

#7

Post by marcosdumay »

andy_ppp wrote: post #6
kumar_navneet wrote: post #4

Amazing stuff, feels really good to see that it is exactly the same as we read in textbooks.

When I looked at chemical symbols before seeing this I had always assumed them to be a sort of vague outline of what was really happening. It's amazing to think that the way chemicals bond is the same in reality as drawn in textbooks.

They choosed a molecule that was similar to its diagram, but that's not always the case.

the main difference is that the diagram is 2D, and molecules are usualy 3D.

Re: High-resolution images of a molecule as it breaks and reforms chemical bonds

#8

Post by adlpz »

ck2 wrote: post #2

Fantastic. http://cdn.physorg.com/newman/gfx/news/hires/2013/2-firsteve... Not sure how they "feel" the interactions without disturbing them but that's why they are the physicists.

Well, as far as I understand it, the interactions (joints) manifest themselves as a larger density of electrons. That's pretty trivial (heh) to detect, just measure electrostatic interaction with a needle, or do some deflection fun.

Re: High-resolution images of a molecule as it breaks and reforms chemical bonds

#9

Post by sp332 »

csense wrote: post #3
ck2 wrote: post #2

Fantastic. http://cdn.physorg.com/newman/gfx/news/hires/2013/2-firsteve... Not sure how they "feel" the interactions without disturbing them but that's why they are the physicists.

> how they "feel" the interactions without disturbing them They can't. I don't know if there are quantum complications at that scale that change this picture, but my basic idea from classical physics is that Newton's Third Law says the probe can't have a force exerted on it by the sample (action) without also simultaneously itself exerting a force on the sample (reaction). > The single-atom moving finger of the nc-AF…

Since the molecule is only heated momentarily to induce the reaction, it is cold before and after. The molecule might be effectively "stuck" to the silver surface it's resting on.
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