Dr. Jessie (Yunn-Shin) Shiue, IAMS joint appointment Sr. Research Scientist, received her Ph.D. in Ceramic Science & Engineering (currently Materials Science & Engineering) from Rutgers University, USA. She joined Academia Sinica in 2005 and the IAMS in 2021. Her research in the past decade has mostly been related to development and applications of electron microscopy (EM). She is the PI of the advanced materials characterization lab (AMC lab) that is currently supported by the Academia Sinica iMATE program and the IAMS.
Q : Please tell us a bit about your background and experiences working in IAMS
A : I have been collaborating with Dr. Yuh-Lin Wang and Dr. Tsyr-Yan Yu from IAMS for many years. They are both great scientists, and I enjoy working with them very much. My main R&D work in the past decade was to develop a TEM (transmission electron microscope) phase plate system which was capable of seeing certain nano-structures in unstained soft materials. It was a wonderful experience for me since I got to revise a TEM system to the way I liked. My team and I learned a lot about the inside & out of the TEM system.
During the past two years, I have worked on planning and installing the most advanced double spherical aberration-corrected transmission electron microscope for the Academia Sinica, and the IAMS administrative team was a great help! I am very grateful for their professional support, so I was able to accomplish this difficult mission efficiently.
Q : Could you please share with us what is so special about this new spherical aberration-corrected transmission electron microscope (AC-TEM) system?
A : This is the first double aberration-corrected TEM system in Taiwan. How to construct a special AC-TEM room is a topic of research papers [1,2]. In order for our newly installed system to achieve the designed resolution of 53 pm, any disturbances from the lab environment had to be carefully evaluated. We evaluated the target site three different times when we started planning this mission. The site evaluation reports indicated the so called “precision lab” (located in the Academia Sinica’s interdisciplinary research building), failed in all the environmental requirements, including the floor vibration, the magnetic field, and the acoustic noises; even the ceiling height was insufficient! It is possible when this old “precision lab” was built ~10 years ago, the room was designed based on the old TEM system. However, the aberration-corrected TEM has advanced significantly in the past decade, thus the environmental needs are stricter nowadays. After some huge efforts in construction & renovation, we finally resolved all the problems and set up a real precision lab for the new AC-TEM system.
The main AC-TEM unit is shown in the photos. All the control units are located in a separate room. The main unit is equipped with a set of active anti-vibration systems to cancel the floor vibration. As shown in the photo, the main unit room is equipped with the active magnetic cancellation system with wiring on the ceiling and the walls, so it can provide the system with a field 0.05 µT (AC & DC in X, Y, Z directions). The specially designed water cooled radiation panels help in achieving the extremely low drifting spec. for the room temperature ( < 0.05 ℃/ min & < 0.2℃/ hr ) with undetectable air flow.
With this advanced system we have already seen several cases that revealed structures which were something that could not be seen or identified under a conventional field emission TEM system. It is a significant advantage for materials researchers to be able to see the structure inside a material which was previously unable to be revealed.
Q : Any specific designs of this AC-TEM you think worthy mentioning to researchers from IAMS?
A : Yes, besides the advancement in the Cs-correctors for TEM & STEM, I am truly amazed by the performance of the new cold field emission gun (CFEG) as well as the new EDS (energy dispersive x-ray spectroscopy) system equipped on this new AC-TEM. The field emission gun is the source for the system. Without a stable electron source, nothing can work in an EM system. The cold field emission gun is known to be a bright source with a long lifetime while the trade-off conventionally is the quick degradation of the probe current. The new vacuum technology (to reach 10-9 Pa) used on this CFEG can now provide a stable CFEG source with a significantly lighter weight and occupying much less space. We are lucky this latest CFEG system was just released and equipped onto this AC-TEM; otherwise, we probably wouldn’t be able to install the AC-TEM in the Sinica due to the insufficient room height.
The latest EDS system equipped on this AC-TEM is also amazing. With a 3-fold advanced new design to improve the pole piece (the heart of TEM) space, the EDS detector area, and the special specimen holder, the solid angle for EDS available on this system is~1.4sr. Simply put, in this new AC-TEM system, one can get highly efficient EDS signals without sacrificing the resolution. The two items were trade-offs for each other in the previous TEM systems. I am truly happy for our users that they get to enjoy such a nice system.
References
[1] “Room design for high-performance electron microscopy”, D. A. Muller, E. J. Kirkland, M. G. Thomas, J. L. Grazul, L. Fitting, M. Weyland, Ultramicroscopy 106, 1033–1040 (2006).
[2] “Face-lift for new JEOL JEM-ARM 200F instruments”, K. Hahn, Microscopy Conference, Univ. Regensburg, Regensburg, Germany, Aug. 25–30, 2013.
