Speeding Up STM Imaging

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."

Building a STM

[Aglassis]

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

[Potor]

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

[jamesh]

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:

[aussie_a]

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

Re:

[Sentri]

Is a pixel bigger or smaller than an atom?

Re:

[niceone]

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:

[account_deleted]

Comment removed based on user account deletion

Re:

[frieko]

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

I had to laugh

[Anonymous Coward]

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

[ParaShoot]

Wow, this guy must be psychotic!

Fixed.

Re:

[WindBourne]

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:

[notmuchtosay]

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

[WindBourne]

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..

[mrbluze]

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:

[prefect42]

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..

[IWannaBeAnAC]

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

[AlphaLop]

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

1000x1kHz

[evwah]

you mean like... one megahertz?

Sampling rate is limiting factor?

[Anonymous Coward]

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

Re:Sampling rate is limiting factor?

[ndg123]

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:

[jibster]

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 tim

Re:

[jibster]

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

Re:

[ndg123]

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 th

Clarification of the above idiot troll

[timster]

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

Mismatch

[Lally Singh]

So.. is the speedup 100 or 1000?

Fabulous STM photos

[ribuck]

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?

[Pseudonym]

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:

[Anonymous Coward]

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:

[TrunkBurger]

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

[Reservoir Penguin]

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.

Possibility to observe viruses in real time?

[master_p]

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

[Doc Ruby]

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

[CodeShark]

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 t

What's the use of a telescope

[AlpineR]

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

An attempt to add some science.

[compumike]

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 in