How Does the Scanning Helium Ion Microscope Compare to Electron Microscopes?

[Leopold Infeld]

How is this microscope going to be way way better than the electron microscope? Does anyone know the significance of this piece of equipment?

Website links would also be nice...

thanks

 

[Claude Bile]

http://nanotechwire.com/news.asp?nid=2120&ntid=121&pg=1

Helium Ions have a much shorter wavelength than electrons for a given acceleration potential because of their greater mass. The minimum resolvable distance you can get (for any microscope) is roughly half the wavelength, so the shorter wavelength means SHIMs potentially can achieve much higher resolutions than standard SEMs.

I'd venture the SHIM will offer maybe a thousand fold increase in resolution, pushing resolvable distances down to the order of picometers, giving us a glance at the 'picoscopic' world for the first time.

Claude.

 

[Leopold Infeld]

Have there been any advancements in this field? Like papers, developements etc. I heard that this microscope has been in development for 10 years already.. what have they beeen doing during then?

thanks again

LI

 

[Claude Bile]

Since the product is being developed by a commercial venture, information about their progress is likely to be scarce. Access to patents is probably the best way to get information on the SHIM, that is, if they have submitted any.

Claude.

 

[Leopold Infeld]

How do I get hold of patents?

thanx

 

[Claude Bile]

Go the US Patent Office website.

http://www.uspto.gov/

Claude.

 

[Leopold Infeld]

do u mean to say that except for ALIS, no one has ever thought about this idea before??

 

[Claude Bile]

Potentially people have, however ALIS seem to have been the first to forsee the current roadblocks present in improving SEMs, and thus got a head start in front of everyone else in developing the SHIM (i.e. they were able to 'sell' the idea of a SHIM first). Getting the idea is one thing - getting people to part with their cash to fund your idea is another entirely!

The reason other groups don't jump on the bandwagon is twofold. ALIS has a head-start, which means they won't be able to capitalise on the advantages (i.e. a monopoly) that come with developing something this early in the technological life-cycle. Secondly, the technology isn't proven yet, the ALIS (well, its backers anyway) is taking a gamble in spending all this money developing this product when there is no guarantee that a) It will work and b) There will be demand for it if they do develop it, at the price they can make it for.

Once the technology has been proven to both a) work and b) make money, you will see other companies start to develop their own SHIMs.

Claude.

 

[Leopold Infeld]

Ok, thanks claude, I have to submit this report in two weeks time and information is as scarce as desert water since its such a new technology. All the information that I have are no way near my comprehension since there are still no layman articles yet.

 

[Claude Bile]

There is plenty of information on Scanning Electron Microscopes though, a Scanning Helium Ion Micorscope will still operate on the same fundamental principle - using charged particles with extremely short wavelengths (compared to optical wavelengths) to achieve super-high resolution. A lot of information available of SEMs will still apply to SHIMs as well in a broad sense.

For your report...

You should mention the diffraction limit, and what diffraction limited resolution means. This will allow you to make a solid connection between the wavelength of the particle and resolution - a connection you will need when explaining the advantages (i.e. improved resolution) of using helium ions as charged particles rather than electron.

You should also mention some of the technical challenges facing SHIMs - namely finding sources and detectors for helium ions. Also, the heavier mass of the helium ion means they are harder to 'steer' into the right position than electrons - meaning you need stronger magnetic fields to control everything.

The highly technical details of the SHIM are unlikely to make good reading, so I wouldn't bother mentioning them. For a report for a non-specialised audience, you just want to give them the 'gist'. Keep in mind that the most fascinating thing people will likely find about the SHIM is the fact that when it is developed, people will start breaking records in terms of being to resolve tiny objects, the next step in the microscopic -> nanoscopic -> picoscopic progression.

I hope that little rant provides some direction for your report. Good luck.

Claude.

 

[sdemjanenko]

i guess the main problem with a scanning helium ion microscope would be the extra mass of the ion compared to the election. It might end up causing damage to the sample.

 

[Leopold Infeld]

Wow, Claude, I am going to reference u in my report, thanks so much. I juz realized that diffraction limit thing.

I actually am going to do two microscopes in one paper now. The other is on STORM, some new technique developed at Harvard by Xiaowei Zhuang et. al.

And sdemjanenko, there will be negligible sample damage as helium ions produce no appreciable sputtering. Even for life science applications, helium ions are light enuff so that they don't damage the delicate sample. But other ions like Gallium FIBs could damage the sample.

 

[kawikdx225]

Some info about the SHIM.
The SHIM uses a single atom for it's emission source.
A single helium ion generates many secondary electrons so very low beam currents can be used without loosing signal to noise.
The surface interaction is very different from a conventional SEM, even at high beam energies the SHIM gives good surface information while the SEM must go to low beam energies and suffer a resolution loss.
Rutherford backscatter imaging has excellent material contrast and is not sensitive to sample charging effects.
The SHIM images low Z materials better than a SEM, carbon nanotubes look amazing and have high contrast compared to a SEM.
These microscopes should be available sometime in 2007.

 

[joking]

I'd venture the SHIM will offer maybe a thousand fold increase in resolution, pushing resolvable distances down to the order of picometers, giving us a glance at the 'picoscopic' world for the first time..

that's impossible. how will you resolve something several orders of magnitude smaller than the probe? at best they're reporting about a quarter of an angstrom.

 

[Claude Bile]

Wait, what?

First of all, why ressurect a year-old thread?

Second, you do know that 0.25 A = 25 pm right? In which case we agree (sort of)?

Claude.

 

[digitalvygr]

Wait, what?

First of all, why ressurect a year-old thread?

Second, you do know that 0.25 A = 25 pm right? In which case we agree (sort of)?

Claude.

I just ran across this thread, interesting stuff. Sorry to "resurrect" it yet again, just interested in the discussion and its new to me.

Seems like the best resolution those ALIS guys are getting is .24 nm, not .25 angstroms as quoted above. So really its not yet pure pico world since that is 240 pm but you can say its bordering into that world. Now the wavelength of helium atoms is a lot smaller than electrons for a given energy so theoretically yes there should be some amazing resolution improvement, but I think it comes down to what kind of spot size they are able to focus it down to, and that is probably the issue.

By way of contrast, the best TEM resolution in the world seems to be from FEI Titan microscopes, their data sheets say that they have a resolution of 80 pm, so a lot better than 240 pm, considering x and y that means pretty much 9 times more information/pixels. However that is transmitting the electrons *through* a thin specimen and then analyzing the diffraction pattern to get that, not relying on a focused spot rastered across a specimen and collecting backscattered electron flux.

So, in theory an ALIS would have probably much better resolution than that by a factor of something like 80 if you could somehow run it in TEM mode (guess you would call that a TAM, transmission atom microscope), but then you probably could have done that a long time ago if it were possible or made sense. I'm guessing somehow atoms knocking into other atoms poses some problems in elastic vs inelastic collisions that you don't have with electrons (the challenge with ALIS was to get the He ion source stable so you could form a small beam, not to emit a bunch of He ions through a specimen in a larger area).

Anyway, regardless of this the ALIS is amazing, and that they figured out a way to make the He stable enough is pretty mind boggling, hats off to those smart kids out in frigid MA! Its a relatively new technology and they probably have room to tweak things down further to even smaller resolutions.

The above is just my guess, I don't know enough to speak to the subject fully, would be great if some microscopy expert would jump in here and tell us why exactly the resolution is not knocking the socks off TEM resolutions...