A trio of new instruments helps researchers sharpen their focus on the world of atoms and molecules.
Few advances in modern science match the potential of nanotechnology to deliver so much from so little.
Nanotechnology involves the manipulation of materials ranging in size from single atoms to several tens of nanometers. One nanometer (nm) is equal to one-billionth of a meter, or about one hundred-thousandth the diameter of a human hair.
Out of these tiny chunks of material, researchers have created almost invisible tubes, particles, pillars, wires and a host of other shapes with special functions.
Iron nanoparticles, for example, can be designed to decontaminate groundwater, while gold nanoparticles may help chemotherapy drugs confine their damage to cancer cells. In sunscreens, nanoparticles block UV rays without leaving a white residue on the skin. In lithium-ion batteries, nanoparticle-based electrodes help power electric cars.
“Nano-whiskers” stitched into fabrics make them lightweight as well as water- and stain-repellent. Nanocatalysts can transform biofeedstocks into fuels, while carbon nanotubes arranged into dense “forests” are being tested for their ability to store hydrogen.
The guiding principle of nanotechnology, says Christopher Kiely, is that a material’s properties – chemical, optical, electrical, thermal and magnetic – can change when it is shrunk to the nanoscale. Normally inert gold, for example, morphs into a catalyst at the nanoscale.
To control the structure and composition of nanomaterials, and to fine-tune and optimize their properties, says Kiely, who directs Lehigh’s Nanocharacterization Lab, requires the ability to observe, measure and manipulate the nanoworld of atoms and molecules.
This, in turn, requires increasingly sophisticated instruments.
Lehigh has long possessed some of the world’s best microscopy and spectroscopy tools. Its collection of electron microscopes is one of the most extensive in American academia. Lehigh was the first university to acquire two aberration-corrected electron microscopes, which can pinpoint the position and chemical identity of individual atoms.
The university’s array of spectroscopy instruments is similarly impressive. Its high-resolution X-ray photoelectron spectrometer (HR-XPS) combines with a new high-sensitivity, low-energy ion-scattering spectrometer (HS-LEIS) to provide an unprecedented view of the surface and subsurface that govern a material’s properties and its reactivity.
In the past two years, Lehigh has acquired funding for several new instruments that will improve researchers’ ability to investigate and control the nanoworld.
- A new JEM-ARM200F aberration-corrected scanning transmission electron microscope, with features customized by Lehigh microscopists, will image atoms with unprecedented resolution. Its low-voltage operation-range improved spectrometry will allow the study of sensitive organic materials, including carbon nanotubes, graphene, polymers and biomaterials.
- The new HS-LEIS, the world’s most sensitive spectrometer for identifying surface atoms, offers a 3,000-fold improvement in sensitivity over conventional spectrometers and also allows for elemental 2-D surface mapping.
- A custom-made NTEGRA marries an atomic force microscope (AFM) with an inverted optical microscope, allowing a specimen to be probed from above by the AFM as it is being observed or optically stimulated by the light microscope.
The new instruments, says Kiely, have the potential to help researchers observe nanomaterials in more dynamic environments, to watch as they react with other materials, and to see how they respond to heat, light and mechanical stress.
These in turn will allow researchers to obtain a more accurate picture of the behavior of objects in the nanoworld.
“We are very adept at making and observing nano-things,” says Kiely. “We have good recipes for making nanoparticles, nanorods, nanowires and nanopillars. And we have improved our ability to examine these things with electron microscopy and spectroscopy and determine their structure and chemistry.”
“However, we are much less adept at taking an individual nanoparticle or nanotube and measuring its physical properties because it is just too small to manipulate and probe.
“We need better tools for analyzing these nanomaterials, and that’s what these new instruments provide.”
Angstrom-level imaging and analysis
The new JEM-ARM200F aberration-corrected STEM, says Masashi Watanabe, enables researchers to correlate the structure and chemistry of materials with 3-D resolution at the angstrom (0.1nm) level.
“This capability will enable us to develop new materials and characterize their properties with unprecedented accuracy,” says Watanabe, an associate professor of materials science and engineering.