by Jennifer Gutierrez
Superman, a Kryptonian, uses his X-Ray
X-ray vision, once the exclusive domain of Superman and his super hero kin, is now a tool in the biological researchers kit. Granted, not every researcher has access to this superpower; the required synchrotron light sources are found only at large research facilities that happen to have a particle accelerator at hand. Still, it is surely worth the bother. Compared to electron microscopy, samples can be imaged in a more natural state without being either embedded or frozen, and they can be larger. Compared to light microscopy, the smaller wavelength of x-ray radiation has the potential to provide higher resolution. Resolution had been complicated by the difficulty in making efficient lenses, but new techniques in both lens design and manufacture are being developed. The lens problem can be circumvented using lens-less microscopy, as employed in a recent paper by Klause Giewekemeyer et al.
The Swiss Light Source at the Paul Scherrer Institut,
a third-generation synchrotron light source. Source.
The data they reported was generated at the Swiss Light Source (SLS) in Villegen, Switzerland, an international center for x-ray microscopy. This facility utilizes a third generation synchrotron light source (whatever that is. I warn you, this is complicated. This and the next paragraphs are for those who care to know how it works). Here the light is generated by first accelerating electrons using a large series of magnets in a linear accelerator, next increasing the acceleration further with more ‘booster’ magnets, and then storing the accelerated electrons in a series of ‘undulators.’ These undulators were developed in the 1970’s at Berkeley and move the electrons around a circular array of periodically-spaced magnets, causing them to slalom as they circle. This step allows the researchers to select the wavelength of electron radiation to be used in the illumination beam (synchrotron light), ranging from ultraviolet to hard x-rays, depending on their imaging goals.