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Speeding Up STM Imaging

kdawson posted more than 6 years ago | from the ready-for-my-close-up-mr.-demille dept.

Science 44

Roland Piquepaille writes "Probably not many of you have used a scanning tunneling microscope (STM), the essential tool of nanoscience. And you might think that it's as easy to take a picture of an atom with an STM as it is to take a shot with your digital camera. In fact, the imaging of individual atoms with an STM is quite slow. Now researchers at Cornell University have shown how to accelerate this process — by adding a radio transmitter, they are able to speed up atomic-level microscopy by a factor of at least 100. A typical STM currently has a sampling rate of about one KHz. This new radio-frequency STM can operate a thousand times faster."

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Building a STM (5, Interesting)

Aglassis (10161) | more than 6 years ago | (#21321385)

Probably not many of you have used a scanning tunneling microscope (STM), the essential tool of nanoscience

You might be surprised [slashdot.org] .

Re:Building a STM (4, Insightful)

Potor (658520) | more than 6 years ago | (#21321741)

And you might think that it's as easy to take a picture of an atom with an STM as it is to take a shot with your digital camera.
has a dumberer sentence ever been uttered in a /. submission?

Re:Building a STM (3, Funny)

jamesh (87723) | more than 6 years ago | (#21321855)

And you might think that it's as easy to take a picture of an atom with an STM as it is to take a shot with your digital camera.

has a dumberer sentence ever been uttered in a /. submission?

I don't think so. The last picture I took with my digital camera had billions of atoms captured. If an STM can only capture a few at a time then it has a lot of catching up to do!

Re:Building a STM (0, Offtopic)

aussie_a (778472) | more than 6 years ago | (#21321961)

That's a mighty fine resolution you've got on your camera if you can make out the atoms!

Re:Building a STM (1)

Sentri (910293) | more than 6 years ago | (#21322453)

Is a pixel bigger or smaller than an atom?

Re:Building a STM (0)

Anonymous Coward | more than 6 years ago | (#21324457)

Usually bigger. Except when you're using an STM, say.

Re:Building a STM (1)

niceone (992278) | more than 6 years ago | (#21322261)

has a dumberer sentence ever been uttered in a /. submission?

I'm not sure, there are plenty of candidates. Leaving that aside, I think you have invented the perfect word for the sequel to "Dumb and Dumber", they can call it: "Dumber and Dumberer" :-)

Re:Building a STM (0)

Anonymous Coward | more than 6 years ago | (#21322819)

I'm not sure, there are plenty of candidates. Leaving that aside, I think you have invented the perfect word for the sequel to "Dumb and Dumber", they can call it: "Dumber and Dumberer" :-)

jesus, has a dumberer [imdb.com] sentence ever been uttered in a /. comment?

 

Re:Building a STM (1)

WeblionX (675030) | more than 6 years ago | (#21323951)

I hate to break it to you, but they already came out with Dumb and Dumberer...

Re:Building a STM (1)

frieko (855745) | more than 6 years ago | (#21325685)

You must be new here. Roland's submissions always make the front page regardless of how dumberer/non-newsworthy they are.

groan (0)

Anonymous Coward | more than 6 years ago | (#21321393)

so now when i go around my physicist friends house not only do i get to see the photos now i have to sit through the movie?

I had to laugh (1, Funny)

Anonymous Coward | more than 6 years ago | (#21321395)

Probably not many of you have used a scanning tunneling microscope (STM), the essential tool of nanoscience
Wow, this guy must be psychic!

Re:I had to laugh (4, Funny)

ParaShoot (992496) | more than 6 years ago | (#21321437)

Wow, this guy must be psychotic!
Fixed.

Re:I had to laugh (1)

WindBourne (631190) | more than 6 years ago | (#21321885)

And yet, others of us, have use them. Pretty common on Universities. In general, most advanced degreed biologists will have had a class in it, so will most biochemists. In addition, a number of Physicists and Engineers will most likely have played with them.

Re:I had to laugh (1)

notmuchtosay (850664) | more than 6 years ago | (#21322861)

Wow, I'm familiar with the STM (I have never used one) but I am not familiar with many people have access or use for one. I thought they were used most for more basic surface physics type of work. Perhaps you are thinking of an SEM or STEM which are now quite common (especially the SEM) and used in a variety of fields? If not, what general use does the STM provide for biology?

Gads, are you right (1)

WindBourne (631190) | more than 6 years ago | (#21325063)

It has been 20+ years since I worked on EMs at Colorado State U. I was thinking of SEMs.

I must be missing something here.. (1)

mrbluze (1034940) | more than 6 years ago | (#21321409)

Now researchers at Cornell University have shown how to accelerate this process -- by adding a radio transmitter, they are able to speed up atomic-level microscopy by a factor of at least 100. A typical STM currently has a sampling rate of about one KHz. This new radio-frequency STM can operate a thousand times faster.
.. but isn't one KHz already pretty fast. I mean, I can't take pictures with my digital camera that fast... more like 0.5Hz.

Re:I must be missing something here.. (1)

prefect42 (141309) | more than 6 years ago | (#21321427)

Depends what the target of the performance measure is. To stick with your camera, if it's 0.5 pictures a second then that's fine, but if it's 0.5 pixels per second...

Re:I must be missing something here.. (4, Informative)

IWannaBeAnAC (653701) | more than 6 years ago | (#21322065)

In an STM machine, there is a single tip that moves over the sample. The sampling is done one pixel at a time, in much the same fashion as the beam of a CRT for example. So 1kHz is rather slow; for your 3 megapixel digital camera it works out at 3000 seconds (almost 1 hour) per frame. So a 1000x increase in speed is really significant!

Wait a bit (2, Funny)

AlphaLop (930759) | more than 6 years ago | (#21321449)

Don't buy one now though, because a model with double the features will be out in 6 months for less $$$ ;)

1000x1kHz (1)

evwah (954864) | more than 6 years ago | (#21321497)

you mean like... one megahertz?

Sampling rate is limiting factor? (2, Informative)

Anonymous Coward | more than 6 years ago | (#21321565)

I thought the limiting factor of SPMs (including STMs) is the feedback loop: one has to keep the probe tip from crashing into the surface as it's dragged back and forth, which means that the scan has to be slow enough that the piezo stack that's moving the probe tip up and down can do its job (limited by speed of sound through the material), as well as the electronics that have to decide how to move the thing in the first place. This might help with the electronics, but 1000x speedup in sampling rate doesn't mean 1000x speedup in imaging speed.

Re:Sampling rate is limiting factor? (4, Informative)

ndg123 (801212) | more than 6 years ago | (#21321647)

On atomically flat surfaces with small scan areas, you can scan in constant height mode (rather than constant current, where the tunneling current is the input to the feedback loop to adjust the probe height ). Still, a 400x400 point image of a 20 x 20 nm area still used to take a couple of minutes. Not 1/1000 second.

Re:Sampling rate is limiting factor? (3, Informative)

jibster (223164) | more than 6 years ago | (#21321745)

The speed a piezo stack responds is related to the speed of sound but not in the way you think.

Each active element of the piezo receives the electrical signal to expand\contract at the speed of electricity through the material. This is usually very close to the speed of light. So the entire stack basically gets the signal move in parallel.

At that point we require a mechanical movement but since we are typically asking it to change by about 1nm/s this doesn't take a long time to do.

One day the response time of the material will become the limiting factor but right now its collecting the electrical signal.

On a separate note, we built STMs all the time in uni. We had a Russian genius who could do amazing things with no budget. He had a technique for making STM tips just by cutting a wire. We got better results from those tips than any of the commercial tips or the techniques published at the time (KOH, drawing etc.).

Re:Sampling rate is limiting factor? (0)

Anonymous Coward | more than 6 years ago | (#21321809)

That's inconsistent with what I know. One might be imaging 5um x 5um at 0.5Hz, with maybe 50nm differences in topology.
 
  Of course, if one is only talking about "atomic resolution" lattice images, this improvement is... limited. Also, I don't think many setups have the probe mounted directly on the piezo stack, but rather have some sort of probe hand to grip the probe.
 
I think cutting Pt-Ir wires with scissors is a de facto standard for constructing SPM tips these days, but it's really cool that you knew the guy that possibly discovered that technique.

Re:Sampling rate is limiting factor? (1)

jibster (223164) | more than 6 years ago | (#21323143)

To be honest with you I was really thinking about AFM for much of the post. I am sure you know, AFM is in many ways identical to STM in reference to the scanning techniques used. Many systems we had converted from AFM to STM mode with just a tip and holder change.

Anyway, we got those AFMs up to very high speeds in some cases several scans a second with little lost resolution. This was typical on a 2x2um area with patterns on the order of 5-10nm.

I remember reading a paper about a modified tapping mode AFM that imaged a 256x256 pixel image at 256Hz and did so clearly enough to show nano-particles wandering around, in realtime, a stepped sample at low T. Actually for all I know now AFM at Khz image rates is common :)

All this was possible with AFM because you didn't have to amplify and read a thiny electrical signal. The technique used here is really very simple and clever, I can't believe it wasn't considered before.

I know Sergay published on his method fro making tips, a knew him 10 years ago but I think he was doing it long before then. I really hope it was him, a nicer guy you'd never meet.

Re:Sampling rate is limiting factor? (1)

ndg123 (801212) | more than 6 years ago | (#21325981)

I remember reading a paper about a modified tapping mode AFM that imaged a 256x256 pixel image at 256Hz and did so clearly enough to show nano-particles wandering around, in realtime, a stepped sample at low T. Actually for all I know now AFM at Khz image rates is common :)

This could be because the particles are being pushed around by the tip - even in tapping or other intermittent force techniques, there is the opportunity for the tip to put mechanical force on the surface. I had the problem with imaging soft surfaces, which were also undergoing electrochemical reactions on the surface - very difficult not to change the structure of a soft polymer residue when you are rastering around on the surface of it.
Mind you, this was 10 years ago now, before I ran away to join the IT circus. I wonder what happened to all those undergrad I taught the STM to....

Boycott Roland, indeed. (-1, Flamebait)

Anonymous Coward | more than 6 years ago | (#21321629)

Slashdot's editors must have a lot of contempt for their users; every submission by that worthless piece-of-shit blogger is a brazen "fuck you" to the Slashdot community. Kdawson, Cmdrtaco et al... it's time to come clean about your financial relationship with this loser and own up to this breach of integrity(among many, many others.) Whether or not it will improve your website's standing, and delay its descent into irrelevance is not important. You owe us an explanation.

Clarification of the above idiot troll (0, Flamebait)

timster (32400) | more than 6 years ago | (#21322263)

New readers may not understand why such vitriol would be addressed to someone who submits interesting science stories to Slashdot. After all, while there is a link to his blog if you click on his name, this is standard practice with story submissions. So what's the big deal?

Well, there was a time back when Roland first started submitting stories where he would put a link to his blog in the summary content, blatantly suggesting that said blog might be a good place to discuss the story. Since there are ad links on his blog, that makes it horrible, evil and self-serving; readers were in an uproar.

Since then the blog link has been restricted to the submitter name at the beginning of the summary (again, standard practice). But some people really cannot ever let go, and we have to put up with silly tags and dumb trolls on every single one of his submissions. Kinda makes you long for the days when almost everyone on Slashdot was more interested in science than name-calling.

Mismatch (1)

Lally Singh (3427) | more than 6 years ago | (#21321681)

So.. is the speedup 100 or 1000?

Tags [8 uninteresting posts precede this] (-1, Offtopic)

Anonymous Coward | more than 6 years ago | (#21321691)

Tags: ohnoitsroland, hellyesitsroland (tagging beta)

(heh)

Fabulous STM photos (4, Interesting)

ribuck (943217) | more than 6 years ago | (#21321721)

If you want to see photos of atoms taken by an STM, there's a great gallery here:

STM Image Gallery
http://www.almaden.ibm.com/vis/stm/gallery.html [ibm.com]

Huh? (2, Interesting)

Pseudonym (62607) | more than 6 years ago | (#21321789)

Essential? Bah! I work in a nanotech lab, and we don't have a STM!

We do have a brand new AFM [wikipedia.org] , though, and it is kinda sluggish. I wonder if this technique would speed up that.

Re:Huh? (1, Informative)

Anonymous Coward | more than 6 years ago | (#21322197)

AFMs are SPMs, as are STMs. But AFMs work on the principle of van der Waals forces, not electrical current, so this wouldn't apply to them. Most AFMs on the market today are actually general-purpose SPMs that can work in AFM mode, with a plethora of optional modes (including STM... you can find an incomplete list of modes here http://en.wikipedia.org/wiki/Scanning_probe_microscopy [wikipedia.org] .

Re:Huh? (1)

TrunkBurger (1188055) | more than 6 years ago | (#21325985)

The fact that an STM sample [generally] must be conductive may make it more limited in applicability vs AFM, but if you are trying to get, for example, *true atomic resolution under ambient conditions*, STM is still the only way to go.

DIY possible (1)

Reservoir Penguin (611789) | more than 6 years ago | (#21321871)

When I was in high school in the Soviet Union around 1992 a friend of mine built one. He used a regular broken sewing needle for the tip, the idea was that when you break a needle the resulting surface is not smooth and there are bumps with a single atom on top.

Re:DIY possible (0, Offtopic)

lufo (949075) | more than 6 years ago | (#21322361)

In Soviet Russia the microscope tunnels you... or whatever.

There's no need to speed it up! (1)

The Standard Deviant (869317) | more than 6 years ago | (#21322185)

I'm working on a project using an AFM and STM, and there is really no problem with the scan rate. There is a monitor which is used for aligning the sample and lowering the cantilever onto the surface. . . but the monitor happens to be a TV, so we have the joy of daytime terrestrial television to pass the time. . .

Possibility to observe viruses in real time? (1)

master_p (608214) | more than 6 years ago | (#21322677)

So will this device allow us to observe viruses in real time? so instead of finding cures for specific viruses that do not work on the next mutation, we could find how viruses operate on atom level and find a cure for that level...much like doing debugging in assembly language.

Read/write Head (1)

Doc Ruby (173196) | more than 6 years ago | (#21322697)

STMs can be used to push together atoms into molecules. If they can get the access time down, and the seek time, put it into a cheap USB enclosure, then I'll take one.

So many posts....so little science (1)

CodeShark (17400) | more than 6 years ago | (#21322931)

Pardon my ignorance, but I also assume that I am in the vast group of /. readers who have no idea what difference the scan rate will make in actual scientific research. I don't really care about how scan tips are made, most of the humor attempts seem flat, and through it all I am asking myself "faster speed must equal ability to do more science, but what's in it for the rest of the world other than a curious factoid. It's kinda like the research that shows that in certain weird cases, scientists are able to slow the speed of light down so profoundly that they can make something go faster than the slowed light transmission rate. Seems cool, but what's the effect on the real world?


Because in the mean time this all seems about as useful to us as the scientific research that was ostensibly to figure out why some men get belly button fuzz and some don't. [slight pot belly, body hair in the navel region, and cotton shirts]. Would someone please explain why a STM is important as the rest of the story?

What's the use of a telescope (1)

AlpineR (32307) | more than 6 years ago | (#21323309)

Your question is similar to "What's the use of a telescope? All it does is make things look bigger! It doesn't have any effect on real life."

Galileo used one of the first telescopes to see that Jupiter is a planet with it's own orbiting moons. Again, that was just a bit of trivia to the common man in his day. But a few centuries later we're using that knowledge to send spacecraft around the solar system.

A new scientific measurement technique is first used to explore fundamental physics and acquire basic knowledge. It could take decades at least before you can point to some everyday object and say "that specific instrument made this possible".

Sometimes the instruments themselves get adapted into everyday tools, like telescope technology being adapted for cameras or Earth-sensing satellites. As somebody else mentioned, maybe high speed ATM could be used as an ultra-high density information storage device. But it's very hard to predict what the everyday impact will be from a bit of fundamental science.

This news is more interesting to those of us who are scientists but didn't know that STM could be done so much faster. Besides saving time to get static scans, high enough speeds would make dynamic scans possible. We could learn a lot about physics, chemistry, and biology if we could watch atoms moving, bonding, and rearranging in real time.

An attempt to add some science. (1)

compumike (454538) | more than 6 years ago | (#21324133)

STMs and AFMs are important because they let us see things much smaller than conventional optical microscopes can. Increasing the scan rate by a factor of 1000 might yield new applications, taking better STM movies, and elucidating mechanisms that run that much faster.

The only public data released on the RF STM stuff seems to be this one lonely chart [kschwabresearch.com] . The gamma variable (on the Y axis) has to do with electrical reflections that come about because of impedance mismatches on transmission lines. For more information, take a look at these lecture notes (2.5MB PDF) [mit.edu] which start from voltage and current, and end with the gamma plane.

In conventional (non-RF) STM, the tunneling current is exponentially related to the distance above the surface. This is a part of why control systems for STMs, which are supposed to keep the tip hovering a few nanometers or less above the surface, are challenging to get right. In general, the surface and scanning tip are kept at a constant bias voltage of a few volts, and there is a feedback loop which attempts to maintain a constant current (and thus constant height over the sample) by adjusting the displacement of the tip.

In this system, it appears that they've found that the small-signal impedance of the tunneling junction varies significantly enough to make a large impact on the reflection coefficient, and (more importantly) that that's a good way to go.

Considering they've released so little technical data, there's only one really obvious savings here to me: noise. If you're an electrical engineer, you'll know that most devices (and thus most circuits) have noise at all frequencies, but that things get particularly bad for low frequencies around DC. This is often called 1/f noise [wikipedia.org] , and if you take f to zero (DC), you've clearly got a problem! Additionally, you get other nasty effects at DC, like drift related to temperature, etc, which tend to be much worse than at high frequencies. By designing their system to work with small signals at high frequencies, they're able to avoid 1/f noise yet still make the height measurement they want. Pretty smart.

--
NerdKits: Educational microcontroller kits for the digital generation. [nerdkits.com]

Not really that special... (0)

Anonymous Coward | more than 6 years ago | (#21327713)

I happen to be a student at Cornell, and we have used mini, portable desktop STM's.
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