Nature Commun. 5, 4219 (2014)

Techniques using inelastic photon or neutron scattering provide access to atomic and molecular motion or collective excitations across a range of time and length scales. When it comes to understanding glass transitions, however, their impact is limited as no probe currently provides access to the appropriate region of time–length space.

But now Yuri Shvyd'ko and colleagues have devised a method to explore this uncharted territory. By combining flat crystal angular dispersive optics with focusing and collimating optics, they have built an ultra-high-resolution inelastic X-ray scattering spectrometer that can bridge the nano- to mesoscale.

Shvyd'ko et al. demonstrated the potential of their technique with studies of the dynamics in glycerol, a prototypical glass-forming liquid. But their method — which should be suitable for most X-ray synchrotron and free-electron laser facilities — opens up a new region of the dynamics landscape, with implications beyond glass physics. And with a few additions, this approach could be developed to enable single-shot measurements, further enhancing spectroscopic performance.