High quality ultrafast transmission electron microscopy using resonant microwave cavities

• Published in: arXiv.org 2018-04
• Main Authors: Verhoeven, W, J F M van Rens, Kieft, E R, Mutsaers, P H A, Luiten, O J
• Format: Article
• Language: English
• Subjects: Apertures; Continuous beams; Electron pulses; Electrons; Emittance; Energy measurement; Holes; Microscopy; Picosecond pulses; Temporal resolution; Transmission electron microscopy
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1709.02205

Ultrashort, low-emittance electron pulses can be created at a high repetition rate by using a TM\(_{110}\) deflection cavity to sweep a continuous beam across an aperture. These pulses can be used for time-resolved electron microscopy with atomic spatial and temporal resolution at relatively large average currents. In order to demonstrate this, a cavity has been inserted in a transmission electron microscope, and picosecond pulses have been created. No significant increase of either emittance or energy spread has been measured for these pulses. At a peak current of \(814\pm2\) pA, the root-mean-square transverse normalized emittance of the electron pulses is \(\varepsilon_{n,x}=(2.7\pm0.1)\cdot 10^{-12}\) m rad in the direction parallel to the streak of the cavity, and \(\varepsilon_{n,y}=(2.5\pm0.1)\cdot 10^{-12}\) m rad in the perpendicular direction for pulses with a pulse length of 1.1-1.3 ps. Under the same conditions, the emittance of the continuous beam is \(\varepsilon_{n,x}=\varepsilon_{n,y}=(2.5\pm0.1)\cdot 10^{-12}\) m rad. Furthermore, for both the pulsed and the continuous beam a full width at half maximum energy spread of \(0.95\pm0.05\) eV has been measured.