11–20 of 34 posts
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.
Earlier quoted context omitted.
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.
In the two variants on the right, their edges seem to be curling upward making a bowl shape. Their edges are also brighter, which perhaps means they are closer to the probe than parts that are farther away. Additionally, the hexagons are also not all the same shape. I assume that's due to the curling.
I would be interested to know if my interpretation of the image is correct, or if the molecule is really flat and what I'm seeing is an artifact.
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…
Best part about that line of reasoning is that it leads directly to the Heisenberg uncertainty principle which is definitely in play here. The act of them measuring the position of each of the atoms means that they can't know that the atoms aren't moving because of the force they exerted. On such small molecules they can likely be reasonably certain they haven't introduced any errors, but for a much larger sample they'll start to have issues where the act of measuring is going to change the outcome.
What I'm waiting for is when someone figures out how to make diffraction gratings for things in the 5nm area so that you can actually image this stuff with photons rather than with an AFM, that should let them handle larger sheets of graphene, and possibly even look at doped graphene with semiconductor properties to get a really awesome understanding of how and why it works (or doesn't).
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…
Obviously there are additional complications at such small scales, and it depends on what you're detecting (measuring / passing through magnetic fields does affect the source since it changes the field), and it depends on what you define as "change" and which quantum mechanics interpretation you subscribe to. I'm just pointing out that the thing being measured doesn't have to be the thing you're investigating, so that law in particular doesn't really imply anything.
Earlier quoted context omitted.
> 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.
Earlier quoted context omitted.
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.
I think you can see some slight 3D effects in the picture: http://cdn.physorg.com/newman/gfx/news/hires/2013/2-firsteve... In the two variants on the right, their edges seem to be curling upward making a bowl shape. Their edges are also brighter, which perhaps means they are closer to the probe than parts that are farther away. Additionally, the hexagons are also not all the same shape. I assume that's due to the cur…
The trouble with all of this is the "picture" is not an actual picture-made-with-photons picture, but a visualization via computer. That isn't to say it's a poor reflection on reality, but that the limitations of the techniques should be accounted for. In this case, the electron density of the overall molecule is being measured. The brighter signals correspond to an increase in local electron density.
In such chemical structures as these, the aromaticity [1] is the main force at play. Without getting too technical, the brighter regions are those with increased electron density. (See figure 4 at the IBM Zurich page on pentacene [2])
The hexagons (and square and pentagons) in fact do not have idealized geometry, but not due to any curling. The unique environment of each carbon is more at play. Symmetry plays a large role; imagine a symmetric vs. unsymmetrical tug-of-war between the carbons with the electrons as the rope. The left hand side and lower right have a dihedral mirror plane, simplifying the density somewhat, where the upper right has a more muddled situation.
Getting back to the flatness, the target molecule is 'mounted' on a suitably uniform surface, such that only one side is being scanned/read by the probe. In a vacuum, the tug of war in the Z direction (into the plane) will cancel out between the +Z and -Z vectors, giving a 'flat' molecule. (Depending on your point of view, either because of this or due to this, each of these molecules has a mirror plane in the plane of the molecule, bisecting each atom.)
Setting all that aside, the entire process is really #$%*& cool, particularly to a chemist. (Yes, those crazy textbook pictures are often reflected in reality. If only the different atoms were color coded, though!)
[1] http://en.wikipedia.org/wiki/Aromaticity [2] http://www.zurich.ibm.com/st/atomic_manipulation/pentacene.h...
Earlier quoted context omitted.
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.
I think you can see some slight 3D effects in the picture: http://cdn.physorg.com/newman/gfx/news/hires/2013/2-firsteve... In the two variants on the right, their edges seem to be curling upward making a bowl shape. Their edges are also brighter, which perhaps means they are closer to the probe than parts that are farther away. Additionally, the hexagons are also not all the same shape. I assume that's due to the cur…
I probably learned it in some chem course, and later forgot as all my math and science got applied to business :(
Earlier quoted context omitted.
> 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…
> > 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). Best part about that line of reasoning i…
Heisenberg uncertainty is much stronger than not being able to observe a system without disturbing it. It's more like, at a physical level, making the probability distribution of a position tight makes the distribution of momentum wide.
[1] http://en.wikipedia.org/wiki/Observer_effect_(physics) [2] http://en.wikipedia.org/wiki/Heisenberg_uncertainty
Earlier quoted context omitted.
I think you can see some slight 3D effects in the picture: http://cdn.physorg.com/newman/gfx/news/hires/2013/2-firsteve... In the two variants on the right, their edges seem to be curling upward making a bowl shape. Their edges are also brighter, which perhaps means they are closer to the probe than parts that are farther away. Additionally, the hexagons are also not all the same shape. I assume that's due to the cur…
I am curious as to the mathematical properties (definitions?) of the hexagonal shape that make it common in natural structures ( http://www.space.com/3611-bizarre-hexagon-spotted-saturn.htm... ). I probably learned it in some chem course, and later forgot as all my math and science got applied to business :(
Electron orbitals can overlap in different ways depending on the geometry of the atom and its electronics. See this for a picture: http://en.wikipedia.org/wiki/File:Benzene_Representations.sv... So, the electrons in a benzene ring really form more of a cloud around the entire ring. You'd expect this to pull the atoms into a perfect circle with the carbon atoms all being equidistance from each other, all else being equal.
However, each carbon atom also has a hydrogen atom attached to it. So now you have a sort of a circle with 6 "strings" attached at points equidistant around the circle all pulling outward, perpendicular to the circle.
Imagine a perfectly circular piece of string with 6 strings attached equidistantly around the circle. You apply an equal force perpendicular to the surface of the circle.
Hopefully you can see how this would result in the original circular string being "deformed" into a hexagon.
It's a far leap from there to say why hexagons are "so common in nature." Are they? Relative to what? I don't know that any of this has anything to do with the shape of that storm you linked to.
Earlier quoted context omitted.
I think you can see some slight 3D effects in the picture: http://cdn.physorg.com/newman/gfx/news/hires/2013/2-firsteve... In the two variants on the right, their edges seem to be curling upward making a bowl shape. Their edges are also brighter, which perhaps means they are closer to the probe than parts that are farther away. Additionally, the hexagons are also not all the same shape. I assume that's due to the cur…
I am curious as to the mathematical properties (definitions?) of the hexagonal shape that make it common in natural structures ( http://www.space.com/3611-bizarre-hexagon-spotted-saturn.htm... ). I probably learned it in some chem course, and later forgot as all my math and science got applied to business :(
As for nature in general, you could probably come up with a convincing argument that boils down to: 6 is a nice round number. It has 2 and 3 as factors.
