Particle Motion Researcher Narayanan Menon Joins UMass Amherst Faculty

AMHERST, Mass. - Physicist Narayanan Menon has joined the University of Massachusetts faculty in the department of physics and astronomy. Menon has conducted extensive research on exactly how a liquid becomes solid, with an eye toward the fundamental differences between liquids and solids.

He is particularly interested in how this process occurs in materials such as glass, which gradually softens rather than abruptly melting when heated beyond the melting point, he said. Glassy liquids are used in a variety of fields, including the materials and plastics industry, according to Menon.

A newer interest is in understanding the unusual properties of a collection of powders or sands, such as the salt in a salt shaker. Menon demonstrated by shaking a transparent canister filled with tiny glass beads. "They can be poured onto the floor and, like a liquid, will not hold onto their form; but if I do not add energy by shaking the jar, they can pile up in a heap, which a liquid could not," he said.

Menon points out that while individual beads or salt grains are transparent, a collection of them appears opaque. That makes it difficult to study the exact movement of the individual beads or grains. Menon overcomes this obstacle by using laser light, which is aimed at sand or grain as it is poured, he said. He can determine exactly how the particles move by analyzing the light that bounces back. His findings have been surprising so far, Menon said. Rather than rubbing against one another, the particles actually separate from each other.

"We would like to be able to explain this movement on the same scientific level as scientists are now able to describe the flow of water," said Menon. The work has applications in industry, agriculture, and in processing pharmaceuticals.

"The study of complex materials is a fascinating subject which also potentially has many applications to future materials development," said John Donoghue, head of the physics and astronomy department. "Menon’s work enhances our department’s and the University’s strength in this area."

Menon earned his Ph.D. in physics from the University of Chicago. He was also educated at the Indian Institute of Technology in Kanpur, India. Before coming to UMass, he conducted postdoctoral research at the University of California at Los Angeles. He won a University of Chicago annual award as the institution’s best graduate teaching assistant.