The Magnetic Moments of Hydrogen-like Atoms

Enrico Fermi

T. E. Phipps, John Bradshaw Taylor

The magnetic moment of the hydrogen atom has been investigated by the atomic ray method introduced by Stern and Gerlach. Atomic hydrogen formed in a discharge tube by the method of R. W. Wood was first used. The ray was formed in a special all-glass slit system of three slits sealed to the discharge tube. The ray was detected by the reduction resulting on contact with a target coated with molybdenum trioxide. A sharply defined blue line against a white background was the result. In the magnetic field the ray was separated into two branching rays. There was also evidence of a central underviated ray which is believed to be due to hydrogen active chemically but probably not in the atomic state. From a measurement of the deflection the magnetic moment of the hydrogen atom was calculated to be one Bohr magneton within the limits of experimental error. This result is of interest because of the questions raised by the new quantum mechanics of Heisenberg, Born, and Jordan, and by the spinning electron theory of Uhlenbeck and Goudsmit. Atomic hydrogen formed by the hot filament method of Langmuir was next used. The increased velocity of the atoms in this case resulted in less separation of the ray, but a deflection was distinctly recorded. Finally, the product formed on exposing a mixture of mercury vapor and hydrogen to ultra-violet light was investigated. This is believed by Cario and Franck, Taylor, and others to be atomic hydrogen. Thus far attempts to form a ray which will reduce the target have been unsuccessful. The reasons for this are being investigated.

W Gough

The magnetic field in a hydrogen atom is calculated for a number of energy eigenstates. The contributions from both the orbital and spin motion of the electron are considered. The field follows the expected magnetic dipole behaviour only at large distances from the proton, and there may also be contributions due to magnetic octupole, 32-poles... moments. The field pattern is illustrated for a number of cases, and these are briefly discussed.

Thomas William Kirkman

Liberman, А. В. Петров

A. Bhattacharya, B. Talukdar

Toroidal dipole (anapole) moments and magnetic fields due to inversion symmetry breaking by an external electric field are studied for the alkali-metal atoms from Li to Rb. It is demonstrated that a hydrogenic atomic model is inadequate for this purpose, while a nonhydrogenic model based on the quantum-defect method yields numbers for the anapole moments in excellent agreement with those predicted by a semiempirical product rule.