Re: [Sci.nanotech] Carbon Games



mike <mikespam@xxxxxxxxxxxxxxxxxxxxxxxxx> writes:
On a dark an' dismal Tue, 01 Apr 2008 21:31:11 -0500, in flickering lamplight,
"Perry E. Metzger"
<perry@xxxxxxxxxxxx> scribed with phoenix qill :

Well.
I know i said fire away, but i wasn't expecting
a flame. The moderators are usually careful
about that....

I believe I stuck pretty strictly to the facts. You may not like the
facts, but that does not make the posting a "flame".

mike <mikespam@xxxxxxxxxxxxxxxxxxxxxxxxx> writes:
So, i was musing on carbon tubes. Specifically
how to make a nice yard or more, single length tube.

I presume you mean a "single wall carbon nanotube".

Yes, that's what i meant.

In my head, almost fully outlined popped this:
A tiny chamber filled with carbon dioxide, kept active
via laser to stop it settling on the walls.

I'm not clear what you mean by that, either. A gas like CO2 doesn't
"settle on walls" at normal temperatures, at least not generally
speaking. (There are circumstances in which some CO2 could be adsorbed
into surfaces, of course, but that's clearly not what you have in mind
here.) I'm also not sure what "kept active via laser" would mean.

Right, first, i don't really know where the carbon dioxide slipped into
the text. Sorry for that, was intended to be all carbon.
The other things like 'normal temp' you refer to?
It's hot, that's what the laser's for, to 'keep it active' a gas.

Carbon doesn't generally become a gas until well past
4000K. Regardless of how you heat it, you will end up with something
that will more or less destroy anything it comes into contact
with. Furthermore, even once turned into a gas, a monatomic form is
not energetically favored until very high temperatures, where
entropy effects overcome the exceptionally strong carbon-carbon bond
energy, thus making your proposal even more unlikely.

A silicon partition with six laser made perforations
(single carbon atom sized) in a hexagon pattern.

A carbon atom is order of magnitude the same size as a silicon
atom. To make a "perforation" this size in a silicon surface would
imply somehow removing individual silicon atoms with a laser.

Which i have read has been done. [might not be silicon, though]

I assure you that no one has yet found a way to remove single atoms in
precisely defined (that is, defined down to an atomic radius) positions
with a laser.

Since an >individual atom is on the order of 100pm (one angstrom) across, you
would need a laser with a wavelength on that order of that length.
<<#>>

As i understand it, the trick is to use two or more lasers at half strength,
creating rings like a ripple in a pond.

You are referring to interference effects. Such effects do not involve
the creation of fields with a characteristic length tens of thousands
of times below the wavelength of the light in use. Again, what you
propose is quite clearly impossible without the use of frequencies far
beyond the ability of current technology to control.

<<#>>
Besides, it isn't clear you could even get the Si atoms to
reliably absorb the x-rays -- they'd likely pass through the surface
instead.)

Okay, what would you suggest?

I have no suggestions -- you are attempting to perform impossible
tasks. Even if I wished to, I could not provide you with ways to
perform them.

Even assuming you could somehow remove single Si atoms by this utterly
impractical means, you could not drill a single atom wide hole through
an Si surface -- the Si atoms would just migrate and close your hole
up.

They would move that fast? I thought we would have them vibrate
and eventually seal the holes, but i was assuming months.

Depassivated Si surfaces are notoriously reactive because they are
very energetically disfavored. The surface will spontaneously
re-arrange to minimize its energy.

And a pressure control between the two, so that when
the holes are filled the difference encourages it to
progress through to the ordered side.

I have no idea what this means, or what relationship it might have to
your mention of CO2 gas or your "hexagonal pattern" "perforations".

To colour it in a little, all it meant was keep the feed side at a slightly
higher pressure, thus encouraging the carbon trapped in the holes to
move through.

As I've already said, if you could get a gas of monatomic carbon at
significant pressure at many thousands of degrees kelvin any
significant pressure, it would immediately vaporize whatever it came
into contact with.

If you could magically keep it from vaporizing what it came into
contact with, it would react instantly with depassivated silicon -- it
would not "move through" holes.

I hypothesize that you somehow think that CO2 could somehow be forced
up to the magic holes you imagine you drill, the carbon atoms would

Apart from the dioxide muck up in my first post,

It makes almost no difference. The rest of your proposal is equally
implausible.

for which i have
already apologised and will not keep doing so, 'coax' is the word i
used because i knew 'forced' was inappropriate.
The Carbon atoms will eventually enter them, if energy is
supplied when things wind down.

I don't know what you mean by "if energy is supplied when things wind down".

[Don't call them magic holes again, please.]

Why not? You need magic to make them, and apparently they have
the magic property of extruding nanotubes out the other side.

somehow magically detach from their bound oxygens, that following this
the carbon would somehow not instantly bond to the Si,

Let them, Next time the laser passes over they will be released.

Any laser capable of breaking a carbon-silicon bond would melt or
vaporize the entire silicon structure. In any case, no carbon atom
will ever travel through an impossible-to-produce single atom wide
hole in a layer of silicon because, were it not so energetic as to
damage the hole itself, it would *always* bond to the Si long before
it could get through the hole, so it essentially wouldn't matter how
often you try.

Or don't use Silicon, another reason it's a bad choice.
What do you suggest as an alternative?

Again, I cannot give you suggestions on how to perform impossible
tasks.

and that somehow by forcing streams of C atoms out the "other side" in a
hexagonal pattern they'd somehow magically form a "nanotube". (Why a
hexagonal pattern? Perhaps you've seen a sketch of a graphene *** in
a magazine and fixated on the hexagons.)

Why not a hexagon? It had to be something, and that just dropped it place.
Do you have a specific reason it cannot be one?

Why not make it into a pentagon, or a tic tac toe grid, or any other
pattern? Even if you could get single C atoms to emerge in a
hexagonal pattern, what is special about a hexagon? Again, perhaps you
are under the misapprehension that a single wall carbon nanotube is
hexagonal in cross section, but it is not, so what is the purpose of a
hexagonal pattern?

Regardless, the idea is implausible. This isn't chocolate frosting
being forced through a pastry tube -- the carbon atoms, even if you
could get them to emerge from your hexagon, will not nicely queue up
and bond to each other, in a hexagonal pattern or in any other pattern.

All that's important is providing the carbon with plenty of
opportunity to bind in some stable ring formation, and still be open
to linking to more from the feed side.

Why would the carbon atoms bond in any particular shape whatsoever?
If they could make it through the holes at all, they'd be arriving in
a temporally randomized pattern, with wildly different energies
(following the Boltzmann distribution for a substance at that
temperature) and would almost certainly leave the holes with quite
uncorrelated trajectories. They would not be within a typical
carbon-carbon bond length of each other, and if they became close
enough to each other there would be no particular reason for them to
form any particular pattern of bonding.

This idea is more or less as plausible as the notion that you could
make humans by forcing bits of homogenized cow through a short slot in
a piece of *** steel.

This doesn't relate, in any way. I am talking about atoms, and that
'notion' above, as you call it is not.

It does relate, in that it is more or less an equally plausible idea.

Perhaps my hypothesis on what you mean is wrong, but I can't think of
any mechanism by which a "hexagonal pattern" of "perforations" in some
Si is going to make you a SWCNT.

You have missed the point and focused on trivia.

No, I understood more or less what you were suggesting. Unfortunately,
it has no possibility of working.

Right at the start was the warning that this was unpolished thoughts,
and i was posting to spark off some feedback.

"Unpolished" is not the word I would have chosen.

I guess this won't work like this, maybe the carbon
will behave better in a liquid mixture?

What do you imagine a "liquid mixture" of "carbon" means? Do you think
that somehow if you can make "carbon" into a "liquid" that it will
work better in your nano-scale pastry decorating tube?

It means exactly what was said, a mixture, not a compound, that
forms a liquid.
How you extrapolated to get that i don't want to know.

It is not clear what you mean here, either. You again seem to be
proposing non-physical things.

(For reference, you can't actually make carbon into a liquid anyway --
at least, not at temperatures below 4000 kelvin and very high
pressures.)

I'm glad i didn't suggest it then :-)

Perhaps you imagine using liquid CO2 would be better for your purpose
than gaseous CO2 -- the answer is no, it won't.

You imagined that, not me.

Perhaps you might state clearly what you are in fact proposing.

It won't work because none of it makes any sense at all.

Yet you still responded to it?

Correct. I've got the bad habit of explaining why incorrect ideas are
incorrect when I encounter them.

It is a suggestion to build nano tubes from carbon gas, by
letting it bond only in set points.

How would you "let it only bond in set points"?

Or perhaps as i have posted here many times, the moderators
know i wouldn't post senseless rubbish,

I'm afraid that the archives, which are astonishingly complete, show
no previous postings from your account. Perhaps you've posted in the
past from other accounts, but I see no reason to assume the moderators
would be able to know that.

I suggest that you re-read the beginning of my original post and
then decide if that was justified.
Still, not too bad considering you didn't understand it.

I understood what you were, more or less, proposing. Unfortunately,
the proposal has no germ of a plausible idea within.


--
Perry E. Metzger perry@xxxxxxxxxxxx

.

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