Irving Herman | Tuning Nanomaterials for a Better World

Irving Herman
Professor of Applied Physics and Applied Mathematics
This profile is included in the publication Excellentia, which features current research of Columbia Engineering faculty members.
                                    Photo by Eileen Barroso

Nanomaterials are viewed as a key part of 21st century manufacturing, with tiny particles whose properties change, depending on their size and shape, and how they are manipulated during the manufacturing process. Applications have already been seen in electronics, pharmaceuticals, and food products. Nano-sized structures can be built in different ways, with pre-selected properties.

For example, nanocrystals, which are intermediate in size between molecules and bulk crystals, emit more blue light when they are successively smaller, due to quantum mechanical effects. Creating such effects becomes more complex when working with assemblies of various nanocomponents

Irving Herman’s research focuses on the fundamental aspects of matter and nanoscience. His work involves the assembly of nanomaterials from nanocomponents, as well as the investigation of the optical and mechanical properties of new materials composed of semiconductor and metal-oxide nanocrystals. His work has potential applications in harvesting light for solar cells, improving electrical and optical communications, and manufacturing products containing nanomaterials.

In one project, Herman synthesizes nanocrystals made of cadmium selenide or iron oxide, and assembles them with electrical fields to create materials that have properties in the nanomaterial intermediate-size range. This technique allows scientists to “tune” the materials to have different properties, based on their size, such as optical properties or magnetic properties. In other projects, Herman assembles three-dimensional arrays of nanocrystals, called supercrystals, which are comprised of many layers of ordered nanocrystals. He also assembles hybrid materials composed of nanocrystals and carbon nanotubes.

Herman’s research also looks at the optical properties of these materials—how they absorb light or emit light after it is absorbed, which is called photoluminescence. He uses a process known as Raman scattering, in which the wavelength or frequency of light after it hits matter is discerned, to better understand the nanomaterial’s properties. This has allowed scientists to couple nanocrystals and other nanocomponents to form nanomaterials. He has used Raman scattering to investigate strain and mechanical properties of nanocrystal films, which helps determine the integrity of products containing nanomaterials.

In addition, Herman teaches a course to Columbia undergraduates, “Physics of the Human Body,” which looks at human physiology through the lens of engineering and the physical sciences. His textbook on this subject explains the mechanics of the static body and the body in motion. It also describes the body’s materials properties, circulation, breathing, the acoustics of speech, as well as the body’s electrical properties.

B.S., Massachusetts Institute of Technology, 1972; Ph.D., MIT, 1977

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