A grant from the National Science Foundation will bring to Colgate University a new field emission scanning electron microscope (FE-SEM), complemented by a suite of high-tech detectors that will enable new research in geology, physics, biology, computer science, and other fields.

“(The detectors) are incredibly versatile,” says principal investigator (PI) Martin Wong, professor of Earth and environmental geosciences. “So many different things happen when electrons hit a surface, and you can use all of these different signals to examine the composition and structure of your sample.”

The $439,805 grant is part of NSF’s Major Research Instrumentation Program. “The objective of the program is to support essential infrastructure for scientific research, but also to train students for high-level research,” explains Wong. The equipment will also benefit researchers throughout Central New York.

Wong teamed up with several co-investigators on the project, including geoscience colleague William Peck and physics professors Ramesh Adhikari and Rebecca Metzler.

With a much smaller wavelength than visible light, electrons allow researchers to image much smaller objects than with an optical microscope. A researcher can get up close to see spores on a fern, hairs on a fly’s leg, nanowires a hundred thousand times thinner than the diameter of a human hair, or extremely small computer circuits.

Adjusting the magnetic field of the scope can cause the flow of electrons in various ways. “You can quickly scan a larger sample or attach it to a single location to analyze something on the nanometer scale,” says Wong.

Wong’s own research focuses on plate tectonics, the formation of mountain ranges and the division of continents. “When rocks are hot and deep, they don’t break, but they flow like silly putty or saltwater taffy,” says Wong, who focuses his research on a region of the American West called the Province basin and distribution area.

Wong analyzes the samples with a special detector called an electron backscatter diffraction detector, which can show how the crystals are oriented inside. “That tells us a lot about the directions in which they were stretching, the temperatures at which they were doing so, and how deep they were in the earth,” he says.

Although Wong is primarily interested in the fundamental science behind such processes, understanding them can also help in the detection of earthquakes and the location of rare minerals.

Geology professor Peck focuses his research closer to home, examining rock formation in the Adirondack Mountains of Ontario and New Jersey. He will be able to use the electron microscope to image samples with what is called the secondary electron detector, capable of displaying a graduated map differentiating minerals.

For further analysis, it will use an X-ray energy spectrometer, capable of measuring the degree to which the flow of electrons excites atoms in a sample, emitting X-rays that provide a fingerprint of the specific elements contained inside. .

Adhikari, assistant professor of physics, works with organic materials. One project, for example, encourages amino acids to self-assemble into tiny nanotubes; another threads nanoscopic computer components into leaf veins. “These materials of biological origin tend to absorb electrons that fall on them, so you don’t see much,” says Adhikari.

This problem can be solved by increasing the beam voltage, but this damages the organic samples. The new microscope, however, can produce high-resolution images at very low voltage without damaging fragile organic components, allowing Adhikari to examine the tiny structures he creates.

Among other uses, it embeds the nanotubes in polyester fabric to create a hydrophobic material capable of filtering oil from water. The leaves can be used to create biodegradable electronic equipment.

The ability to create sharp images at low voltage is also essential to Metzler’s work. The physics professor studies biomineralization, the process by which marine organisms create shells and other hard materials. Some of his work examines the formation of exoskeletons by juvenile barnacles, which can be as small as 100 microns wide.

“Our current scanning microscope cannot detect the crystals that make up their exoskeletons,” says Metzler, who once had to travel 75 miles to Cornell to use his more advanced equipment.

She also studies other species of clams from the Gulf of Mexico, using the X-ray spectrometer to identify elements and the backscatter diffraction detector to examine how crystals are oriented inside the shells to examine how climate change affects the durability of shells over time. .

In addition to these research applications, the microscope will be used by various faculty across campus, studying everything from volcanic eruptions in the Galapagos Islands to models of tools worn at pre-Hispanic archaeological sites.

The equipment is versatile enough that it can be used in classroom demonstrations as well as in the laboratory, Wong says. Countless students will use it for thesis projects over the next two decades; At the same time, exposure to the advanced instrument will help students gain experience that could help them work with microprocessors, nanotechnology, or mining.

“This is widely used equipment with all kinds of research and industrial applications,” says Wong. “Being trained on this will give students an advantage no matter what path they take.” »