Ernest Marsden

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ENGLISH PHYSICIST
Ca. 1888–1970

Ernest Marsden studied at the University of Manchester under Ernest Rutherford and Hans Geiger. Although a physicist, he would help elucidate something of value to all chemists: the internal structure of the atom. This was accomplished by observing the path of α -particles in Rutherford's famous "gold foil experiment," in which it was really the human eye, pressed to a short-focus telescope for hours on end in a thoroughly darkened room, that was the detector.

According to Rutherford, Marsden, a twenty-year-old undergraduate, became involved after Rutherford and Geiger decided that Marsden should begin research work. Rutherford thought that Marsden might be able to discover if α -particles could be scattered through a large angle. Geiger and Marsden spent 1909 in the "gloomy cellar" of the physics laboratories at Manchester, watching for the little sparks that announced the unlikely recoil of α -particles. About 1 in 8,000 did, and this result, published in 1909 as "On a Diffuse Reflection of the α -Particle," formed the basis for Rutherford's nuclear model of the atom and the discovery of the proton.

Geiger and Marsden continued to study the deflection of α -particles, and in 1913 (after observing over 100,000 scintillations at a rate of 5 to 90 per minute) correlated nuclear charge with atomic number . In 1914 and 1915 Marsden continued to study the impact of α -particles on matter; these experiments led to Rutherford's 1919 fortuitous attainment of the alchemist's dream: the artificial transmutation of the elements.

Marsden returned to his native New Zealand in 1915 where, on Rutherford's recommendation, he was appointed professor of physics at Victoria University in Wellington. He held various academic and governmental posts until his retirement in 1954. The national fund for the support of science in New Zealand was renamed the Sir Ernest Marsden Fund in his honor.

SEE ALSO ; Rutherford, Ernest .

Mark A. Pichaj

Bibliography

Chown, Marcus (2001). The Magic Furnace: The Search for the Origins of Atoms. Oxford, U.K.: Oxford University Press.

da Costa Andrade, Edward Neville (1964). Rutherford and the Nature of the Atom. Garden City, NY: Doubleday.

Gamow, George (1958). Matter, Earth and Sky. Englewood Cliffs, NJ: Prentice-Hall.

Shamos, Morris H., ed. (1959). Great Experiments in Physics. New York: Holt, Rinehart & Winston.