The magnetic moment of the palladium atom has been investigated by the Stern-Gerlach method by evaporating the metal from a tungsten boat resistance furnace through beam forming slits of Pyrex glass and allowing the beam to impinge and condense on a glass plate after passing through an inhomogeneous magnetic field. It was found that images too weak to be detected could be developed satisfactorily by the method used by Stern and Gerlach for silver images. No splitting of the beam of palladium atoms was observed although the same field gave a splitting of 0.04 cm for a beam of atomic hydrogen. This indicates that the palladium atom in its normal state has zero magnetic moment in agreement with spectroscopic results giving for its ground term a $^{1}S$.
The magnetic moment of the palladium atom has been investigated by the Stern-Gerlach method by evaporating the metal from a tungsten boat resistance furnace through beam forming slits of Pyrex glass and allowing the beam to impinge and condense on a glass plate after passing through an inhomogeneous magnetic field. It was found that images too weak to be detected could be developed satisfactorily by the method used by Stern and Gerlach for silver images. No splitting of the beam of palladium atoms was observed although the same field gave a splitting of 0.04 cm for a beam of atomic hydrogen. This indicates that the palladium atom in its normal state has zero magnetic moment in agreement with spectroscopic results giving for its ground term a 1S.
The work of Stern and Gerlach in which they determined the magnetic moments of certain atoms and at the same time furnished direct evidence of the theory of space quantization, by deflection of rays of the atoms in an inhomogeneous magnetic field, has been repeated for silver atoms. A simplified apparatus is described, using a silver plated tungsten coil as source of atoms, rather than the furnace used by Stern and Gerlach, which gives trouble in outgassing.The magnetic moment of sodium and potassium. The apparatus was further modified for use with the alkali metals by construction of a liquid air cooled target for receiving the atomic rays and a Pyrex glass device for holding the molten metal during evaporation. The images of the rays on the glass target were made visible by immersing in hydrochloric acid gas, which "fixed" them as the opaque and visible chloride. Distinct images of the separated rays resulting from the action of the magnetic field on the oriented atoms have been obtained and are reproduced. Measurements of the separations show that, within the experimental error, sodium and potassium possess magnetic moments equal to one Bohr magneton, in accord with spectroscopic predictions.
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.
Spin and helicityTraditionally, in textbooks on quantum mechanics, spin is introduced via an idealized Stern-Gerlach experiment in which a non-relativistic beam of silver atoms passes through an inhomogeneous magnetic field.Each atom is treated as a single valence electron of charge -e in an s-state.The subsequent splitting of the beam into two indicates the two-valuedness of Sz, which is related to the value 1/2 for s, and the magnitude of the splitting shows that the magnetic moment /l is related to s by e /l = -~s, me the proportionality factor (the gyromagnetic ratio) being twice as big as the factor that classically gives the magnetic moment due to the orbital angular momentum of a point charge.Historically, however, it seems that the early Stern-Gerlach experiments, begun in 1922, had no influence at all upon the discovery of spin, simply because they were too imprecise.Rather, the concept of spin appeared after a long and tedious battle to understand the splitting patterns and separations in line spectra.Several people had for various reasons discussed classical models of rotating charge distributions but Kronig, in 1924, was the first to show that an electron with spin 1/2 would explain the pattern of what we would today call L • S splitting, as well as anomalies in the Zeeman effect.He realized, though, that the gyromagnetic ratio ( -ejmc) needed for the latter would give L • S splittings twice as big as those observed.It is said that Pauli expressed his negative reaction to Kronig's idea with such vehemence that Kronig never published his work (Mehra and Rechenberg, 1982).Soon thereafter, in 1925, the same idea occurred to Uhlenbeck and Goudsmit (1925), who proceeded to a detailed analysis of the splittings, concluding at first that everything worked beautifully, but then becoming aware, as a consequence of a comment by Heisenberg, of the factor-of-2 inconsistency mentioned above.
Abstract We propose a phenomenological theory of spin behavior in a magnetic field, which explains from the point of view of classical physics the two-valued result of the Stern-Gerlach experiment. The behavior of the spin and intrinsic magnetic moment of an electron wave of an atom in an external magnetic field is considered. We show that in a weak magnetic field, the intrinsic magnetic moment of an electron wave is always oriented parallel to the magnetic field strength vector, while in a strong magnetic field, depending on the initial orientation of the intrinsic magnetic moment, two orientations are realized: either parallel or antiparallel to the magnetic field strength vector. Within the framework of classical electrodynamics, the calculation of the motion of an atomic beam in an inhomogeneous magnetic field is carried out, which reproduces the results of the Stern-Gerlach experiment.
Abstract Some major quantal developments are described in Chapter 10. The Stern-Gerlach experiment is encountered first, wherein a beam of silver atoms is deflected by a magnetic field, leading to a pair of traces on a detecting plate. Next is the proposal that electrons have a new attribute known as spin, used to explain the Stern-Gerlach result, thereby confirming the validity of this new attribute. To account for the structure of the periodic table, the central-field approximation is introduced. In it, electrons in an atom are treated like those in hydrogen, except that they have four not three quantum numbers, the fourth related to spin. The Pauli Exclusion Principle requires that no four can be the same for any electron in the atom, a feature that explains the occurrence of shells in the periodic table. The electronic structure of various atoms is stated, with silver being a giant spin ½ system.