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Interview: Ehsan Nasr Esfahani

Hello Ehsan, it is good to see our customers measuring all over the world as you've been hopping back and forth between the USA and China. Can you tell us more about your research and what benefit you have in measuring in totally different labs?

My research is towards developing new techniques for probing energy storage materials with nanoscale spatial resolution. Most of our high-precision measurements are based on Scanning Probe Microscopy (SPM) methods, where we mostly look at the tiny motion of an SPM probe in different modes. Our labs in Shenzhen and Seattle have different equipment and measurement devices each necessary for a specific type of test. After all, it is a good excuse to travel around!

I've heard before that the future of SPM lies in probes and modes, what's your take on that?

Although SPM is a versatile tool for measuring a variety of different physics right beneath a probe tip, it has quite simple principles: a finger-like probe is touching a sample, feeling a certain behavior. The rest is up to us, how to touch, and how to feel!

Let me give an example. We recently utilized a new "heated probe scheme" in our AFM where a solid state resistor was used to elevate the temperature at the probe tip. If you apply a modulated current at frequency f to the resistor of this probe while it is in touch with the sample, the temperature of the probe and the probe itself starts to oscillate at frequency 2f. It turns out that ions, if present under the probe tip, will be oscillating at frequency 4f. So, it is still the classic AFM contact mode that has been used for decades, yet a new patent-pending and unique method to look at the ionic motion of energy storage materials with an unprecedented resolution has recently been published.

I guess I answered your question, right? But don't forget that the necessary condition is the ability to reliably acquire data!

You were among our first users to benefit from the very latest LabOne release, and you were pretty quick to master it, how useful is it to record images directly from a Line trigger with grid alignment?

Well, it made my life much easier. In the case of imaging it is always beneficial, yet not easy, to have the measured data aligned with the probe motion. It simply made the visualization and post processing more straightforward. I look forward to seeing a real-time imaging tool in your next versions. That would be exciting.

Do you think that 6 demodulators per input are enough or are you already dreaming of more? How many images can you make at once?

Well, my general rule for many cases is "the more, the merrier" and I guess this is not an exception. But 6 demodulators combined with a quad PID are just more than enough for measuring even complicated high harmonic physics. I easily get 12 images at once.

How would you characterize Zurich Instruments' support over multiple sites? We want an honest answer.

My time in China was very limited and I had to learn to operate our brand new HF2LI in a brief period of time. In addition to the user-friendly LabOne interface, the Zurich Instruments support made a valuable contribution to shortening the learning time and solving the challenges we were facing. In general, they are very responsive, always coming up with a practical solution in a short period of time. I found them to be knowledgeable also about many applications and not only about their own products.

How is it to be a visiting scientist in China? What do you enjoy the most from this cultural exchange?

It is a great and unique experience to be a visiting scientist in China because of the broad resources available to scientists. In terms of cultural exchange, the food and the culture around the food is definitely the most interesting. We have lots of group lunches and dinners every week where tons of different dishes are being ordered!

Ehsan Nasr Esfahani

Ehsan Nasr Esfahani, Clean Energy Institute, University of Washington in Seattle and Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China

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