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Felix Bloch

educator , physicist

Felix Bloch was a Swiss-American physicist and Nobel Prize winner best known for his discovery of nuclear induction — the physical principle that led to the development of the powerful analytical technique of nuclear magnetic resonance spectroscopy.

Background

Bloch, Felix was born on October 23, 1905 in Zurich, Switzerland. Son of Gustav and Agnes (Mayer) Bloch.

Education

In accordance with the wishes of his father, a wholesale grain merchant, he enrolled in 1924 at the Swiss Federal Institute of Technology to study engineering, but soon transferred to the institute’s physics division, where he came under the influence of Erwin Schrödinger. Schrödinger, along with Niels Bohr, Max Born, Werner Heisenberg, and others, was at that time formulating quantum mechanics — the fundamental principles underpinning almost all of modern physics.

Career

Although Bloch arrived just a few years too late to contribute to the formulation of quantum mechanics, his life’s work was to lie in its direct application. Thus his Ph.D, thesis (with Heisenberg in Leipzig) developed the analogue in the case of a crystalline solid to the electron structure of the atom. This paved the way for an understanding of electrical conduction in metals, semiconductors, and insulators, and even today Bloch states and Bloch functions are familiar concepts to any physics undergraduate.

Upon Hitler’s ascent to power in the spring of 1933, Bloch left Germany and was later invited to a position at Stanford University, which, like other centers of learning, was eager to avail itself of the talent to be found among the European refugees arriving in the United States. There, Bloch conceived of a method for detecting the magnetic moment of the recently discovered neutron (i.e., that it behaves like a small magnet) and, together with L. W. Alvarez, made the first accurate measurement of its value.

During World War II Bloch was engaged in the early stages of the Manhattan Project to manufacture the atomic bomb and, later, in the development of methods of countering radar detection of airplanes. The enormous refinements in radio techniques that were made during the war years suggested to him a new and more precise method of measuring the neutron magnetic moment. His idea, based on rigorous theoretical analysis and borne out in practice at Stanford in 1945, was that a neutron or nucleus with nonzero magnetic moment, when subject to a magnetic field, would absorb radio waves of a frequency determined by the value of its magnetic moment — a process later termed magnetic induction. The corollary to this is that if the magnetic moment of a particular nucleus is known, its presence within a material sample can be detected. This new technique of materials assessment was christened nuclear magnetic resonance (NMR) spectroscopy. It is a prime example of how basic scientific research, seemingly specialized and without immediate practical application, can produce in the long term a tool of great practical utility. NMR spectroscopy revolutionized chemistry and biochemistry and contributed to clinical medicine by offering a noninvasive diagnostic method, safer than X-ray tomography and in certain respects superior to it.

Works

  • Contributor about 80 articles on atomic physics to science publications, since 1927.

Membership

Fellow American Physical Society (president 1965-1966), American Academy Arts and Sciences, Royal Society Edinburgh. Member National Academy Sciences, Royal Dutch Academy Sciences.

Connections

Married Lore C. Misch, March 14, 1940. Children: George J., Daniel A., Frank S., Ruth.

father:
Gustav Bloch

mother:
Agnes (Mayer) Bloch

spouse:
Lore C. Misch

children:
George J. Bloch

Daniel A. Bloch

Frank S. Bloch

Ruth Bloch

colleague:
Edward Purcell

Felix Bloch and Edward Mills Purcell were awarded the 1952 Nobel Prize for "their development of new ways and methods for nuclear magnetic precision measurements."

References

  • Nobel Prize Winners This outstanding series presents detailed accounts of the lives and work of the 876 men, women, and institutions that earned the Nobel Prize from its inception in 1901.
    1987