Stem-Gerlach beam experiments

Stem-Gerlach experiment The demonstration of the quantization of electron spin by passing a beam of atoms through a magnetic field, stick structure See line structure. stock solution A solution stored in concentrated form, stoichiometric coefficients The numbers multiplying chemical formulas in a chemical equation. 

When atoms are placed in a magnetic field, the energy levels of the electrons split into more than one component These splittings are small (no more than 10 3 eV, even in strong magnetic fields), but can be seen in the line spectra of atoms this is called the Zeeman effect. There are other manifestations. For example, in an inhomogeneous (i.e. non-uniform) field, a beam of atoms can be deflected, and splits into several components this is the Stem-Gerlach experiment, and is illustrated in Fig. 5.5. 

Fig. 5.5 the Stem-Gerlach experiment, showing a beam of atoms splitting into two on passing Ihrough an inhomogeneous field generated by specially shaped pole pieces. 

When a beam of He atoms similarly undergoes a Stem-Gerlach experiment, the beam passes through without being deflected. This implies that there is no magnetic field associated with the He atoms, even though there are two electrons present. Thus, the two electrons in the atom must have opposite spins—one "up" and one "down"— which cancel each other out and provide no overall magnetic moment. 

The origin of EPR spectroscopy lies in the fact that electrons have both electrostatic charge and spin angular momentum. The former is observed by electron-deflection from negatively charged surfaces, in for example, a cathode ray oscilloscope the latter is easily verifiable in the classic Stem-Gerlach experiment [29, 30] in which a beam of S-state silver atoms is observed to split into two separate beams... 

Silver s unpaired 5s electron causes silver to be paramagnetic, hi fact, an early demonstration of electron spin—called the Stem-Gerlach experiment—involved the interaction of a beam of silver atoms with a magnetic field. An atom or ion in which aU electrons are paired is not... 

The most famous experiment related to spin was the Stem-Gerlach experiment [13] in 1922. In that experiment, silver was vaporized in an oven and allowed to exit as a beam, which traveled between a long pair of magnet poles each machined to a knife edge. From chemistry, we know Ag has one outer electron and the Schrodinger model would describe the electron orbital occupancy as (li )(2i 2p ) 3s 3p 3d ) As 4d °)(5 ). As the Ag atoms traveled through the long path, the... 

In the Stem-Gerlach experiment a narrow beam of sodium atoms in the ground state was passed through a highly nonuniform magnetic field (Figure E7.15). What nonuniformity of the magnetic field dBldz should be provided so that the distance between the components of the sodium atoms split beam fixed on the screen will be equal to (5 = 6 mm The installation dimensions are /j = 10 cm, Ij = 15 cm, speed of atoms is equal to Ug = 400 m/sec. The whole installation is placed in a hermetic vacuum shield. 

However, the first results were misleading. It is a difficult experiment to do properly, because the atoms collide with one another in the beam. An atom moving in one direction might easily be knocked by its neighbors into a different direction. When Stem and Gerlach repeated their experiment, they used a much less dense beam of atoms, thereby reducing the num-... 

Stem used a beam of silver atoms for his experiment. As the silver atoms streamed toward the detector, they were nudged, at a right angle to their motion, by an applied magnetic field that caused the beam to spread out. Thus, the detector saw a slightly widened beam of silver atoms. The doubters, like Debye, expected the beam atoms to be distributed continuously across the widened dimensions. Stem and Gerlach found something dra-... 

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