Dudley R. Herschbach described the work that won him a Nobel Prize yesterday as taking place on "the lunatic fringe" of chemistry when he began his experiments 20 years ago.

Today, his research on the way molecules interact as they form new materials is a cornerstone of physical science, according to chemists here and elsewhere.

Herschbach, the fifth member of the Chemistry department to win the Nobel Prize, shares it with a former colleague, Tiawan-born Yuan T. Lee of the University of California at Berkeley, and with John C. Polanyi, a German-born professor at the University of Toronto.

Working with Lee, who was then a Harvard post-doctoral fellow, Herschbach developed molecular beam and spectroscopic techniques that allow researchers to observe the collisions of molecules.

The two crossed the molecular beams in a vacuum, which agitated the molecules. They then used mathematical and experimental methods to determine the velocity and energy content of the resulting reactions, which take place in less then a trillionth of a second.

Polanyi worked independently to achieve the same end. He took a different tack, using the infrared emissions of newly formed molecules to measure the energy transfer that individual molecules undergo when in chemical reactions.

"Scientifically, our work is very complimentary," Polanyi said in a telephone interview from Toronto.

"[Herschbach] lines up the molecules and he can determine what angles, and what patterns of movement they take as they dance," Polanyi said. "My methods tell you about vibration and rotation."

Before the scientists' work, chemists could study only the behavior of large groups of molecules.

"Usually, chemistry deals with huge crowds of molecules at once," Herschbach said. "But as you know, crowds don't always reveal the character of individuals very well."

Herschbach said yesterday that he first considered using beams to study molecular behavior when, as a Stanford undergraduate in the 1950s, a professor mentioned early laser beams.

"The professor made a reference, a sentence really, about the early lasers and how they affected molecules, and I said `Gee, that's how I'd like to study Chemistry.'" Herschbach recalled.

After coming to Harvard as a graduate student, Herschbach was unusually directed in his studies, acquiring the skills necessary to use beams in his later work, said E. Bright Wilson, who together with now deceased Professor George B. Kistiakowski, Herschbach recalls as formative influences during his graduate days.

"I think something special about his career is that he really prepared himself for what he's doing. Most people just fall into it," Wilson said.

After a stint as a junior fellow in the society of fellows, Herschbach went to the University of California at Berkeley as a junior professor. There, Herschbach said he meet Lee, then a graduate student, and worked with him on initial stages of his research.