8 Atomic Physics 8.6 Related Experiments
Stern-Gerlach experiment with a stepper motor and interface
P2511111
Principle A beam of potassium atoms generated in a hot furnace travels along a specific path in a magnetic two-wire field. Because of the magnetic moment of the potassium atoms, the nonhomogeneity of the field appliesa force at right angles to the directionof their motion. The potassiumatoms are thereby deflected from their path. By measuring the density of the beam of particles in a plane of detection lying behind the magnetic field, it is possible to draw conclusions as to the magnitude and direction of the magnetic moment of the potassium atoms.
For more details refer to page 197.
Electron spin resonance
P2511200 Principle With electron spin resonance (ESR) spectroscopy compounds having unpaired electrons can be studied. The physical background of ESR is similar to that of nuclear magnetic resonance (NMR), but with this technique electron spins are excited instead of spins of atomic nuclei. The g-factor of a DPPH (Di-phenylpikrylhydrazyl) and the halfwidth of the absorption line are determined, using the ESR apparatus.
For more details refer to page 202.
Rutherford experiment with MCA
P2522115 Principle The relationship between the angle of scattering and the rate of scattering of alpha-particles by gold foil is examined with a semiconductor detector. This detector has a detection probability of 1for alpha-particles and virtually no zero effect, so that the number of pulses agrees exactly with the number of alphaparticles striking the detector. In order to obtain maximum possible counting rates, a measurement geometry is used which dates back to Chadwick. It is also possible in this case to shift the foil and source in an axial direction (thus deviating from Chadwick's original apparatus), so that the angle of scattering can be varied over a wide range.
For more details refer to page 247.
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