Continuing size reduction in semiconductor manufacturing, and a push toward atomic time and spatial resolution in the field of structural dynamics require, require the development of novel charged-particle sources and instruments. Electron microscopes have recently been combined with pulsed lasers to provide temporal resolution down to sub-ps scale. However, techniques such as radio-frequency cavities provide an alternative. RF fields can also be used to reduce the longitudinal bunch length of pulsed electron beams, such as used for ultrafast electron diffraction (UED). Here the central issue is to gain control over space-charge forces which tend to destroy the quality of the beam. This requires spatial and temporal shaping of the particle bunches from the moment of creation until delivery at the target. I will discuss recent results in which such control allowed single-shot diffraction patterns of crystalline atomic samples to be obtained as well as sub-ps temporal resolution. To extend this technique to biological samples, an electron source that allows for a larger transverse coherence length for a similar target area is being developed, based on trapped atoms. Measurements show that electron temperatures several orders of magnitude lower than for a photo-emission source can be achieved. At the same time, such a source provides unique ion beams with temperatures in the mK range and energy spread well below 1 eV. These may have applications in focused-ion beam instruments, where probesize limitations due to chromatic aberrations can be eliminated.
|Title of host publication||Symposium Monochromatic ion and electron beams : new sources and applications, University Paris-Sud 11, Orsay, France, 10 February 2011|
|Place of Publication||S.l.|
|Publication status||Published - 2011|