DENSsolutions Installing South Korea's second Stream system at Seoul National University

The team at SNU (From left to right) Prof Jungwon Park, Back Kyu Choi, Minyoung Lee and Junyoung Heo.

With the second ever installation of a Stream LPEM Solution in South Korea, we get an insider’s look at the microscopy laboratory at the Seoul National University. We interviewed Prof Jungwon Park from the National Center for Inter-University Research Facilities to find out how our solutions will benefit their research when investigating synthetic mechanisms of inorganic nanocrystals.

Can you tell us a bit about the microscopy facility at Seoul National University SNU?

Seoul National University has a shared research facility called NCIRF (National Center for Inter-University Research Facilities) that has specialities in various fields of analysis, such as organic, inorganic, surface analysis, and x-ray techniques. NCIRF also has a special team in electron microscopy, which provides SEM, TEM, and other pretreatment equipment including FIB and Nanomill.

This shared facility was established around 30 years ago. Recently, two spherical aberration-corrected TEM and STEM, JEM-ARM200F, were installed, providing atomic-resolution electron microscopy images. Also, in our own center, the Institute for Basic Science Center for Nanoparticle Research, we have our own JEOL JEM-2100F TEM in our building which is utilized routinely for a lot of in situ EM studies.

What type of applications are your users interested in with regards to the Stream system installed?

Our users are interested in various nanocrystal dynamics. Regarding the Stream system, we are expecting to investigate the synthetic mechanism of colloidal inorganic nanocrystals by changing the liquid cell temperature and injected precursor solution. Also, we are planning to investigate transformation phenomena of colloidal nanocrystals in various liquid environments. Moreover, we are expecting to observe polymers or proteins in liquid, and their stimuli-responsive reactions using the Stream system.

What particular features of the DENSsolutions Stream solution attracted you to the system?

When it comes to liquid cell TEM experiments, it is crucial to ensure that a controlled amount of liquid is injected to the desired position, while minimizing the decrease in spatial resolution of TEM stemming from the window bulging effect. In this sense, the Stream system by DENSsolutions was quite attractive to us.

With ensured liquid flow from Nano-cell design, controlled injection of liquid, as well as mitigated window- bulging originating from the pressure-based liquid pump, and also along with the liquid heating control system, the Stream solution seemed to help us to design various in situ liquid cell systems which were unachievable with other in situ holders.

What particular features of Stream attracted you to the system?

For our experiments, it was essential to find a way to control the flux of the liquid within the liquid cell in order to look at reactions or processes occurring on the location of the electron beam. This is something we were unable to do with previous generations of holders and chips. The DENSsolutions Stream system is the only system that allows you to completely control the liquid flux. This unique capability is what intrigued us most about the system.

Moreover, as a result of the Nano-cell’s special inlet-outlet design, we are also able to fully control the pressure and liquid thickness. Other features that we found very attractive include the control systems like the heating control unit and the pressure-based pump, which are considerably more elaborate compared to what we had in the past.

In your experience so far, how have you found the Stream system?

At first, the Stream system was quite complicated to us since a lot of elaborate systems were installed. But soon we realized that it was much simpler than it seemed. The method to assemble the Stream holder was easy compared to other liquid cell TEM holders, and the way to control the injection solution was straightforward. And since a lot of O rings are used to encapsulate the Nano-cell, the holder seems to be very stable without leakage problems while operating the TEM. Also, the heating control software was upgraded from the Wildfire version, making it much easier to use the program.

DENSsolutions Prof. Jungwon Park

Jungwon Park, Ph.D
Associate Professor | Seoul National University

Jungwon Park received his B.S. degree from the Department of Chemistry, POSTECH, South Korea, in 2003, and his Ph.D. degree from the Department of Chemistry, University of California, Berkeley, in 2012. After a post-doc with the School of Engineering and Applied Sciences, Harvard University, he started a faculty position with the School of Chemical and Biological Engineering, Seoul National University, in 2016, and he currently serves as an associate professor jointly affiliated with the Center for Nanoparticle Research, Institute for Basic Science (IBS). His research areas include the in-situ study of nanomaterials, liquid-phase TEM, phase transitions, interface chemistry, and low-dimensional materials.

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