Pieter Zeeman
Zeeman, Pieter (1865-1943) was a Dutch physicist who became known for his discoveries in spectroscopy, the study and analysis of spectra of light. In 1896, he discovered what is now called the Zeeman effect, the splitting of spectral lines by a magnetic field. The theory for this phenomenon was developed by Hendrik Antoon Lorentz, and the two scientists shared the 1902 Nobel Prize in physics for their work. Through the Zeeman effect, astronomers measure the strength of the magnetic field on the surface of stars.
Zeeman was born May 25, 1865, in Zonnemaire, a small village on the isle of Schouwen in Zeeland, the Netherlands. His father. Catharinus Farandmus Zeeman, was a minister, and his mother was Wilhelmina (Worst) Zeeman. After completing secondary school at Zierikzee, a town 5 miles (8 kilometers) away, Zeeman went to the city of Delft to study for two years. Zeeman first showed his great ability for science when in 1883 he wrote on the aurora borealis and the article was published in the scientific journal Nature. Zeeman met influential scientists, including the future Nobel Prize winner Dutch physicist Heike Kamerlingh Onnes, with whom he became friends. Kamerlingh Onnes discovered superconductivity in 1911 when he found that mercury could, at extremely low temperatures, conduct electric current without resistance.
Zeeman entered the University of Leiden in 1885. Two of his professors were Kamerlingh Onnes and Lorentz. He obtained his doctor's degree in 1893, and then became a lecturer at the University of Leiden. He researched the interaction between magnetism and light.
In 1896, Zseman first observed the effect that was to be named for him. His work verified experimentally Lorentz's theoretical work on electrons. Lorentz had followed up on Scottish physicist James Clerk Maxwell 's electromagnetic theory of electricity and of light. Maxwell had showed that light consists of waves in combined electric and magnetic fields, called electromagnetic waves.
In 1892, Lorentz began to formulate a theory of what he and others would later call electrons. Believing that tiny, electrically charged particles existed in matter, Lorentz deduced that oscillations of these minute charged particles produced electromagnetic waves, including light and the radio waves.
Zeeman studied the light emitted by an atom by using a spectroscopic apparatus to break the light into different colors. The colors appear as bright lines called spectral lines. The Zeeman effect is the splitting of a single spectral line into two or more lines. He created this effect by placing a substance emitting light in a magnetic field. A magnetic field is the influence that a magnet or electric current creates in the region around it. Zeeman demonstrated the effect of a strong magnetic field on the oscillations by measuring the apparent change in the wavelength of the light produced and showing that the spectral line split into three components.
The Zeeman effect is an influence that magnetism has on light. The effect changes the color of the light emitted (sent out) by atoms. The parts of an atom that actually emit light are negatively charged particles called electrons. An electron emits light when it jumps from a higher energy level to a lower energy level. The color of the light depends on the difference between the levels. The atoms in a substance will emit light when they are given enough energy—for example, by heating the substance.
The Zeeman effect occurs because electrons have magnetism resulting from their charge and motion. The effect occurs when the magnetic fields created by electrons of a particular kind of atom interact with the external magnetic field. Depending on how an electron is oriented, this interaction may increase or decrease the electron's energy slightly. Each new energy level makes a different spectral line. In this way, a single spectral line splits into two more lines when atoms are in a magnetic field.
In 1897, Zeeman began teaching at the University of Amsterdam. In 1908, he became director of their physics laboratory. In 1923, the university built a new laboratory that later became known as the Zeeman Laboratory of the University of Amsterdam. Zeeman remained at the university until his retirement in 1935.
In addition to the Nobel Prize, Zeeman also received many other awards and honors, including the Rumford Medal of the Royal Society of London and the Henry Draper Medal of the American National Academy of Sciences.