Magnetic Rabi experiment

If we transform the problem to a frame rotating with the microwave field, it is static and cannot induce transitions. The transformation to the rotating frame, often used to describe two level magnetic resonance experiments, is discussed by Salwen37 and Rabi et al.3H. 

The experience at the Radiation Lab was very important for Purcell s professional development. Thrown together with more senior physicists, he learned about their pre-Rad Lab work in physics. Particularly influential, as Purcell acknowledged, were the physicists from Rabi s laboratory at Columbia. Purcell learned from Rabi (to whom he reported), Ramsey, Zacharias, and Henry Torrey about Rabi s prewar magnetic resonance experiments, and as the war wore on, ideas began to take shape in Purcell s thinking. 

The first molecular beam magnetic resonance experiments were with 12 molecules, but in 1940 Kusch, Millman and Rabi [5,6] extended the method to paramagnetic atoms and including... 

The problem of transit-time broadening was recognized many years ago in electric or magnetic resonance spectroscopy in molecular beams [1253]. In these Rabi experiments [1254], the natural linewidth of the radio frequency or microwave transitions is extremely small because the spontaneous transition probability is, according to Vol. 1, (2.22), proportional to co. The spectral widths of the microwave or RF lines are therefore determined mainly by the transit time AT = d/v of molecules with the mean velocity v through the interaction zone in the C field (Fig. 5.10a) with length d. 

However there is one exception the most precise experimental value for the ground state hyperfine splitting [14] is 3.2 standard deviations below the theory if we add the experimental and the theoretical uncertainties in quadrature. This experiment has been performed in a 0.8 Tesla magnetic field where a Breit-Rabi... 

The pioneering experiments on H2, HD and D2 were performed by Kellogg, Rabi, Ramsey and Zacharias in 1939 [3], Their principal objectives were to determine the magnetic moments of the proton and deuteron, and the electric quadrupole moment of the deuteron. The sorry events of 1939 to 1945 brought the work to an untimely... 

On one visit to Stern s molecular beam laboratory Rabi made a casual suggestion to Stern for an experiment, which brought the immediate response Why don t you do it Rabi was told it was an honor to receive such an invitation from Stern. I was in no position to refuse an honor, said Rabi. Rabi s experiment introduced a novel configuration of the magnetic field for deflecting particles in a molecular beam—a configuration now called the Rabi field. 

When Rabi read about Stern s surprising result for the magnetic moment of the proton, he decided it was necessary to redo the experiment to verify the unexpected result. Furthermore,... 

Because of the inherent weaknesses with the first experiment on the proton, the experimental results, reported in 1934, were given with the large uncertainty of 10 percent. But even with the imprecision of the results, they were provocative. Rabi s first measured result of the magnetic moment of the proton was 3.15 ... 

The objective of the 1938 experiments was to measure the magnetic moments of the hydrogen and deuterium nuclei as accurately as possible. In 1938, however, a new sense of promise inspired the members of Rabi s group as they prepared to apply the new resonance method to the hydrogens and to measure the magnetic moments of the proton and the deuteron to a new level of precision. Eventually, this objective was accompHshed successfully, but not without surprises that led to new basic knowledge about the atomic nucleus. 

This particular quantum transition later rose to stardom in the world of physics. It was the same transition that Rabi and his students, shortly after the war, found to be at odds with Dirac theory, and it was this transition that led to a new value for the electron s magnetic moment. By 1947, this transition had gained prominence from an experiment on earthbound hydrogen atoms soon this same transition would assume galactic significance. Also, this same transition would become the basis for the most accurate atomic clock, which was developed in the late 1950s (discussed in Chapter 18). 

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