Four-dimensional ultrafast electron microscopy
Electron microscopy is arguably the most powerful tool for spatial imaging of structures. As such, 2D and 3D microscopies provide static structures with subnanometer and increasingly with Angstrom-scale spatial resolution. Here we report the development of 4D ultrafast electron microscopy, whose capability imparts another dimension to imaging in general and to dynamics in particular. We demonstrate its versatility by recording images and diffraction patterns of crystalline and amorphous materials and images of biological cells. The electron packets, which were generated with femtosecond laser pulses, have a de Broglie wavelength of 0.0335 angstrom at 120 keV and have as low as one electron per pulse. With such few particles, doses of few electrons per square Angstrom, and ultrafast temporal duration, the long sought after but hitherto unrealized quest for ultrafast electron microscopy has been realized. Ultrafast electron microscopy should have an impact on all areas of microscopy, including biological imaging.
Additional Information© 2005 by The National Academy of Sciences of the USA. Contributed by Ahmed H. Zewail, March 30, 2005. Published online before print May 9, 2005. A.H.Z. thanks Prof. David Tirrell for his encouragement and timely support of our vision. We acknowledge the genuine interest of Prof. Grant Jensen in the development of UEM and Dr. William Tivol for his generous assistance and stimulating discussions. We also thank Bill Anderson and Mike Stekelenburg of the FEI Company and Dr. Chuck Crawford of Kimball Physics, Inc., for invaluable discussions and assistance, and Dr. Wanzhong He for the biological specimen preparation. This work was supported by the National Science Foundation and the California Institute of Technology.
Published - LOBpnas05.pdf