First-of-its-Kind Hard X-ray Free-Electron Laser Images Intact Viruses

Zothecula writes "In a paper published in the current edition of Nature, an international team of scientists describe how they obtained the world's first single-shot images of intact viruses – a technology that could ultimately lead to moving video of molecules, viruses and live microbes. Another paper by the same team describes how they were also able to successfully utilize a new shortcut for determining the 3D structures of proteins. Both advances were achieved using the world's first hard X-ray free-electron laser – the Linac Coherent Light Source (LCLS) – which scientists hope could revolutionize the study of life."

Comments

intact after X-ray?

[faa]

"hard X-ray free-electron laser" - are the viruses realy intact after such a burst?

Re:intact after X-ray?

[Rakshasa Taisab]

Who cares about what happens to them after the burst... Kinda like old erotic images; how old and wrinkly they are now doesn't matter.

Re:intact after X-ray?

[jamesh]

Who cares about what happens to them after the burst

While a movie of bursting viruses might be interesting, it won't be as scientifically useful as a movie of a virus that is (mostly) unaffected by having the movie taken of it.

This sort of stuff is like determining where a basketball is by throwing tennis balls at it and seeing where they land. You can only throw a few before the basketball becomes so affected by the tennis balls that you don't know where it is anymore (or how fast it's moving)...

Great Title

[AMindLost]

Just trying to get the title to make sense made my head hurt!

Re:Great Title

[mooingyak]

I-just wanted to Hard free-comment on-this-story with intact-hyphens.

Link

[Monkey-Man2000]

How about a link to the paper?

Re:Link

[faa]

oh, now that's been clarified

Simple answer: No.

[YuppieScum]

FTFA:

The duration of its individual pulses is incredibly short – a few millionths of a billionth of a second. That’s still long enough to cause its subjects to vaporize , but that doesn’t happen until after their pictures have been snapped.

OK, this was in the second paragraph, but even so...

Re:Simple answer: No.

[PolygamousRanchKid]

That’s still long enough to cause its subjects to vaporize , but that doesn’t happen until after their pictures have been snapped.

So that means that the TSA will not be using hard X-rays . . . um, doesn't it?

Re:Simple answer: No.

[Defenestrar]

You mean "normal" X-rays which is defined as the electromagnetic spectrum between 10 and 10,000 pm? As opposed to the backscatter X-rays which could range anywhere in the electromagnetic spectrum between 10 and 10,000 pm? Attenuation (transmission) and backscatter are different techniques for X-ray imaging - but they both still use X-rays. It's like the difference of looking at a stain glass window from the inside or the outside of the church - in both cases it's sunlight that does the illumination.

It does get more complicated when you talk about specific wavelength, intensity, and etc... when you try to measure dosage. But all X-ray methods utilize ionizing radiation which is carcinogenic. Dose may be a very small portion of what you get every day, or in the case of the X-ray laser here, it may be enough to vaporize you.

Re:Worth a Nobelprize

[oodaloop]

No way. This doesn't begin to compare to what Obama did in the first two weeks of his presidency.

Video?

[Jedi1USA]

How would this lead to moving video when the subject matter is vaporized in the process?

"Laser", but not really

[Mt._Honkey]

I am a physicist-in-training (grad student), and when I first heard of "free electron lasers" I was extremely impressed, because getting electrons into a multi-keV energy state that can lase without atoms involved sounded nearly impossible. Turns out it is, because these are not actually "lasers" the sense of Light Amplification by Stimulated Emission of Radiation. There is no population inversion as in real lasers.

The name of this specific FEL, the "Linac Coherent Light Source", is a much more correct name. They shoot electrons through a wiggler, and as they wiggle they emit coherent photons. Coherency is they key property of laser light, but the name refers to the method of light creation more than the actual output. I don't know why the x-ray community has felt the need to use this misleading name.

Re:"Laser", but not really

[Anonymous Coward]

Not only that, a Free electron laser (FEL) is only spatially coherent, not temporally coherent. This is a drawback of the "single-pass" method of X-Ray generation in FELs. Essentially, you can compare a FEL to amplified spontaneous emission (ASE) that is common in devices like superluminescent diodes. The bunching of electrons in FELs along the wiggler leads to different bunches that emit temporally coherent X-Rays, but across the entire FEL there are a large number of such bunches resulting in a spectral output that consists of a wide range of x-ray energies with many peaks overlayed on top.

There isn't any temporally coherent X-Ray laser to date. People have proposed using very pure diamond crystals as X-Ray mirrors to set up a feedback cavity to a FEL, thus allowing for true temporal coherence just as in the case of traditional lasers that rely on a feedback cavity to establish temporal coherence. There are also some more esoteric proposals involving using a coherent "seed" laser, to seed the FEL oscillations, but it involves using 500+ order harmonics via non-linear effects.

For the curious (and those with access to Nature) - this is a very nice, informative review on FELs: http://www.nature.com/nphoton/journal/v4/n12/abs/nphoton.2010.239.html

Re:"Laser", but not really

[kindbud]

Because the word "laser" has taken on a broader meaning since it was coined, so that it is used to refer generically to any coherent electromagnetic wave generating device or phenomena. Laser is the Kleenex of physics.

Re:"Laser", but not really

[joe_frisch]

In a conventional laser you have a laser rod and mirrors. You charge the rod and it starts to emit spontaneous light. That light is reflected from the mirrors and passes through the rod many times, gaining energy from spontaneous emission each time. Eventually you extract the available energy in the rod and a partially coherent beam is emitted from one of the partially transparent mirrors.

Now imagine that rather than use mirrors, you used a lot of rods is series. The effect would be the same, spontaneous emission from the first rod would be amplified in the downstream rods until it saturated. The light emitted would be very similar to the light from the rod and mirror system.

The LCLS (and other SASE FELs) work the same way - there are many undulators (33 for us) and the X-rays from the first undulator are amplified as they travel through the later undulators. The LCLS has 20-30 exponential gain lengths so the amplification finally saturates.

You are right that it is not longitudinally coherent, but that is true of many lasers. Various techniques are used in conventional lasers to make they fully coherent. Similar tricks (seeding) will be added to the LCLS in the near future. We will probably do the first tests of seeded longitudinally coherent operation later this year.

Also, when we run with very short pulses (few femtoseconds) the beam is nearly longitudinally coherent (due to transform limit).

---- Joe Frisch
SLAC / LCLS

Video from Stanford onn LCLS

[failedlogic]

Here's a video (animation) from Stanford explaining how the LCLC works.

http://lcls.slac.stanford.edu/AnimationViewLCLS.aspx

Re:nothing exciting here

[chudnall]

But that's the best picture they can get of the largest virus known to mankind?

That's just the first part. Then they send it over to the CSI guys and say "enhance!"

Should diffraction be called "imaging"?

[asadodetira]

They are not obtaining images but diffraction patterns, which after applying sophisticated methods lets them reconstruct a configuration that is consistent with the diffraction image, to within some margin of error. This techniques tend to better for confirming proposed structures that to getting it from scratch.