Hans Dehmelt, who shared the 1989 Nobel Prize in Physics for developing methods to trap a single ion or electron, allowing for a more precise way to measure their properties, died March 7 in Seattle. He was 94.

His wife, Diana Dundore, confirmed his death.

Dr. Dehmelt devised a configuration of magnetic and electric fields known as an ion trap that serves as a cage for charged particles like ions and electrons. Once the particle was trapped, scientists could study it.

In 1973, Dr. Dehmelt used the technique to observe a single isolated electron. He was later able to observe single ions in the trap.

Dr. Dehmelt’s work “allowed us to measure the electron’s magnetism” — and that of its antiparticle, the positron — and to make “ultraprecise spectroscopic measurements of a single trapped ion,” Robert Van Dyck Jr., a physics professor emeritus at the University of Washington, where he worked with Dr. Dehmelt, wrote in an email.