Fifty-five years of molecular beams

Journal Article · Sat May 01 00:00:00 EDT 1993 · Bulletin of the American Physical Society

OSTI ID:281641

Ramsey, N F

The history of molecular beams since the invention of molecular beam magnetic resonance is discussed. Rabi`s 1937 theoretical paper on resonance transitions led Rabi, Zacharias, Millman and Kusch to measure various nuclear magnetic moments by magnetic resonance. Kellogg, Rabi, Ramsey and Zacharias found a multiple line radio frequency spectrum in H{sub 2}, D{sub 2}, and HD which enabled them to measure not only the nuclear magnetic moments but also internal molecular interactions including that of the deuteron electric quadrupole moment. The method was successfully extended to atoms. In 1947 Nafe, Nelson and Rabi found that the observed hyperfine separations in atomic hydrogen and deuterium differed from theoretical predictions and Lamb and Retherford soon thereafter observed the large Lamb shift in the atomic fine structures; these two discoveries were the principal incentives for the development of QED, which was confirmed by Kusch`s measurement of the electron magnetic moment. Ramsey`s separated oscillatory field method increased the accuracy and frequency range of the resonance method and provided the basis for accurate atomic clocks. Townes and his associates used a molecular beam for the first Maser as did Goldenberg, Klepper and Ramsey for the atomic hydrogen maser. Many nuclear, atomic and molecular properties have been measured with the molecular beam magnetic resonance. Van der Waal`s molecules and highly excited Rydberg atoms have been examined. Laser spectroscopy has been extensively studied with atomic beams and lasers have been used for state selection and excitation. Wieman and others used atomic beams to study parity and time reversal symmetry. Atomic beams have been slowed by laser cooling and Phillips and others have shown that the atoms can be cooled to about one micro-Kelvin, well below the Doppler limit. Collision experiments between two beams, often from jet sources, provided extensive and detailed information about molecular interactions.

• OSTI ID: 281641
• Report Number(s): CONF-9305421--
• Journal Information: Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 3 Vol. 38; ISSN BAPSA6; ISSN 0003-0503
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
DEUTERIUM
FULLERENES
HISTORICAL ASPECTS
HYDROGEN
MOLECULAR BEAMS
MOLECULE COLLISIONS
NUCLEAR MAGNETIC RESONANCE