SCANNING PROBE MICROSCOPY continued
or touch the surface with PeakForce Tapping to measure the contact current. “One of the strengths of AFM is the ability to work in situ,” Muel- ler says. “With this probe and PeakForce Tapping, one can do new in situ functional studies of photocatalysis, fuel cells, batteries, but also biosen- sors and other devices.” He adds, “It’s a vast range of opportunities.”
Big data from small structures “The rest of the world is changing dramatically—using Google Scholar
and Facebook—but in science we use the same scope and searches that we used five years ago,” Kalinin says. The sharing of information among people is not being replicated in data from microscopes.
Kalinin realizes the limitations of a single person analyzing information. The data from his microscope goes to his computer, where he analyzes the results. “But, I only analyze [a] fraction of data collected,” he says, “and the conclusions can be limited by my expectations and experi- ence.” To get more from that data, Kalinin wants to make it available to more eyes and minds. There’s a lot of data to share, because an SPM can generate 10 gigabytes in 10 minutes. So, his team is learning how to capture the full stream of data and make it available to other scientists. “We’re going from small-data microscopy to big-data microscopy,” he says. “We don’t always need all of the data, but we would not know that
a priori.” The tools that Kalinin and his colleagues developed—deployed via GitHub on the web—and associated YouTube training videos are available for free.6 specific applications.
These tools can even be customized by scientists for Viewing in a vacuum
The first SPMs operated in a vacuum, and some still do. Scienta Omicron (Taunusstein, Germany) makes SPM platforms that work in an ultrahigh vacuum—like 10-10
torr—to keep samples clean and enable work at liq-
uid-helium temperatures. With these capabilities researchers can study fundamental electronic structures of materials. “A contaminant-free sample is essential for a good experiment, and the lower the tempera- ture, the lower the thermal noise contribution to the data,” says David Laken, sales manager at Scienta Omicron. “Plus, at low temperatures, your molecule of interest can be frozen to the surface for study.”
Such low temperatures can be very costly to produce, because liquid helium is expensive. In a 4
He system, it costs about $1000 per dose of the
coolant. Scienta Omicron offers platforms that are cryogen-free. “There have been cryogen-free coolers for some time,” says Laken, “but as the cooling process uses mechanical pumps, generating disruptive me- chanical vibrations, they have not been able to be effectively combined with SPMs until recently.”
Since the early days, SPM systems have been used to move individual atoms. According to Laken, “Leading researchers use our systems to create single-atom qubits,” which can be used as the computing units of a quantum computers.
It’s a long way from stimulating a frog’s legs to building a quantum computer, but science often connects unexpected phenomena. To- day’s connections between atomic structures and teeny movements would surely amaze Galvani, and the result is a continuing march toward greater discoveries, technologies, and consumer products.
References 1. Kalinin, S.V.; Strelcov, E. et al. Big, deep, and smart data in scanning
probe microscopy. ACS Nano 2016; doi: 10.1021/acsnano.6b04212. 2.
http://ifim.ornl.gov/ 3. Kumar, R.; Tokranov, A. et al. In situ and operando investigations of failure mechanisms of the solid electrolyte interphase on silicon elec- trodes. ACS Energy Letters 2016; doi: 10.1021/acsenergylett.6b00284.
4. Desbief, S.; Dubois, P. et al. Nanoscale investigation of the electrical properties in semiconductor polymer-carbon nanotube hybrid mate- rials. Nanoscale 2012; doi: 10.1039/c2nr11888b.
5. Nellist, M.R.; Chen, Y. et al. Atomic force microscopy with nanoelec- trode tips for high resolution electrochemical, nanoadhesion and nanoelectrical imaging. Nanotechnology 2017; doi:10.1088/1361- 6528/aa5839.
6.
http://ifim.ornl.gov/resources.html
Mike May is a freelance writer and editor living in Florida. He can be reached at
mikemay1959@gmail.com.
AMERICAN LABORATORY 30 JUNE/JULY 2017
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