Ultrafast Electron Microscopy
Transmission electron microscopy (TEM) is one of the most powerful imaging techniques. Currently, the TEM enables imaging of three-dimensional (3D) structures at the atomic scale. However, the temporal resolution of TEM is often limited by the recording rate of the imaging device used. Thus, to overcome such a limit, a pulsed laser source is applied to trigger the photoemission and, subsequently, to obtain a higher temporal resolution.
The ultrafast electron microscopy (UEM or UTEM) is, essentially, a pump-probe technique where an ultrafast laser pump pulse excites the material and a delayed probe – electron pulse – detects the response at a specific time, correlated with the pump pulse. Accordingly, then the temporal resolution is no longer limited by the speed of the electron detector as it is determined by both the pump laser pulse duration and probe electron pulse. Therefore, the generation of short electron pulses is also quite important and is often carried out using a second or third harmonic of the fundamental frequency of the same ultrafast laser. Furthermore, the UEM requires the laser output with a high pulse repetition rate and high output stability to preserve a high signal-to-noise ratio (SNR).
The PHAROS and CARBIDE laser series with femtosecond pulse duration, high repetition rate, and high output stability are excellent sources for ultrafast electron microscopy, making it another promising ultrafast technology.
- 100 fs – 20 ps tunable pulse duration
- 4 mJ maximum pulse energy
- 20 W maximum output power
- Single-shot – 1 MHz repetition rate
- Automated harmonic generators (up to 5th harmonic)
- 190 fs – 20 ps tunable pulse duration
- 2 mJ maximum pulse energy
- 80 W maximum output power
- Single-shot – 2 MHz repetition rate
- Air-cooled version
- 515 nm, 343 nm, 258 nm, and 206 nm outputs
- Simple selection of active harmonic
- Simultaneous or switchable outputs
- Customizable or high-power and -energy models
- 10 fs – 20 ps pulse duration range
- 500 – 2000 nm wavelength range
- High-resolution voice coil driven delay line
- Integrated controller
- Pulse-analysis software
Imaging Nanometer Phonon Softening at Crystal Surface Steps with 4D Ultrafast Electron Microscopy
Y. Zhang, and D. J. Flannigan, (2021).
UEMtomaton: A Source-Available Platform to Aid in Start-up of Ultrafast Electron Microscopy Labs
D. X. Du, S. A. Reisbick, and D. J. Flannigan, Ultramicroscopy 223, 113235 (2021).
Unraveling the Ultrafast Hot Electron Dynamics in Semiconductor Nanowires
L. Wittenbecher, E. V. Boström, J. Vogelsang, S. Lehman, K. A. Dick, C. Verdozzi, D. Zigmantas, and A. Mikkelsen, ACS Nano 1 (15), 1133-1144 (2021).
Characterization of a time-resolved electron microscope with a Schottky field emission gun
P. K. Olshin, M. Drabbels, and U. J. Lorenz, Structural Dynamics 5 (7), 054304 (2020).
Coherent interaction between free electrons and a photonic cavity
K. Wang, R. Dahan, M. Shentcis, Y. Kauffmann, A. B. Hayun, O. Reinhardt, S. Tsesses, and I. Kaminer, Nature 7810 (582), 50-54 (2020).
Development of analytical ultrafast transmission electron microscopy based on laser-driven Schottky field emission
C. Zhu, D. Zheng, H. Wang, M. Zhang, Z. Li, S. Sun, P. Xu, H. Tian, Z. Li, H. Yang et al., Ultramicroscopy 209, 112887 (2020).
High-resolution analogue of time-domain phonon spectroscopy in the transmission electron microscope
E. J. VandenBussche, and D. J. Flannigan, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 2186 (378), 20190598 (2020).
Influence of Discrete Defects on Observed Acoustic–Phonon Dynamics in Layered Materials Probed with Ultrafast Electron Microscopy
S. A. Reisbick, Y. Zhang, and D. J. Flannigan, The Journal of Physical Chemistry A 9 (124), 1877-1884 (2020).
Mitigating Damage to Hybrid Perovskites Using Pulsed-Beam TEM
E. J. VandenBussche, C. P. Clark, R. J. Holmes, and D. J. Flannigan, ACS Omega 49 (5), 31867-31871 (2020).
Nanoscale Imaging of Unusual Photoacoustic Waves in Thin Flake VTe2
A. Nakamura, T. Shimojima, Y. Chiashi, M. Kamitani, H. Sakai, S. Ishiwata, H. Li, and K. Ishizaka, Nano Letters 7 (20), 4932-4938 (2020).