Experiments during Wintersemester 2019
E-Mail: m.pakdaman (at) fkf.mpg.de
Room: 1.936 Tel.: 64863
The Zeeman-effect contains all effects that can be observed related to spectral lines whose emitters are exposed to a magnetic field. It is differentiated between the “normal” and the “anomalous” Zeeman-effect.
For the normal Zeeman-effect it is J=L, the spins couple to S=0 and every line splits into a triplet. At the anomalous Zeeman-effect, where J=L+S (S≠ 0), every line splits into more than three lines (if the degeneracy is totally lifted). Furthermore, there exists the so called Paschen-Back effect, where the L-S-coupling is small compared to the energy of the single magnetic moments in a strong external magnetic field. In the experiment the splitting of the 587,6nm He-line in a strong variable magnetic field will be examined with a Fabry-Pérot-Etalon and evaluated with the aid of a digital camera.
Multiplet systems, term schemes, selection rules, normal and anomalous Zeeman-effect, Paschen-Back effect, Fabry-Pérot spectrometer, hall probe
E-Mail: Q.He (at) fkf.mpg.de
Room: 1.905 Tel.: 64869
The Hall-Effect is an important method for the characterisation of metals and semiconductors. From Hall-measurements one gain information about the electrical parameters of a semiconductor, like the mobility, the charge carrier density and the band gap. In the students lab you measure the Hall voltage in dependence of temperature, magnetic field and the longitudinal current of an undoped and p-doped Ge-crystal. Consequential you can deduce the relevant parameter like band gap, electron and hole mobility as well as their particular densities. Key words: Band structure of a semiconductor; Transport in semiconductors; Charge carrier mobility in an electron gas; Scattering and relaxation; Doping; Magneto-transport and Hall-Effect
E-Mail: r.walter (at) pi4.uni-stuttgart.de
Room: 1.909 Tel.: 64871
Quantum Analogs is an acoustical experiment designed to explain wave mechanics. The basis of the experiment is the analogy between the mathematical description of an electron in a potential (Schrödinger equation) und the behavior of ordinary sound waves in air (Helmholtz equation). The major advantage of acoustical experiments hereby is that sound-phenomena appear on an accessible time and length scale for humans. The experimental setup allows to investigate acoustical analogies with one- and three-dimensional quantum mechanical systems. Acoustical analogues to the hydrogen atom and hydrogen molecule and the dispersion in one-dimensional acoustical semiconductors are examined.
Schrödinger equation, hydrogen atom, hydrogen molecule, Bragg condition, band gap, reciprocal space, dispersion relation, Brillouin zone, reduced zone scheme
E-Mail: olga.iakutkina (at) pi1.physik.uni-stuttgart.de
Room: 1.518 Tel.: 64865
In the last 20 years atomic force microscopy has become next to scanning electron microscopy the second standard method for high-resolution microscopy. With a resolution in the nanometer range it surpasses diffraction-limited optical microscopes by a factor of 1000. Its greatest advantage compared to other high-resolution methods is that is does neither requires vacuum nor comple sample preparation.
In the lab you will learn the handling of the AFM with calibration samples and “everyday life samples”. The obtained pictures will then be edited and analyzed with an image processing software. Methods like 2-D Fourier filtering and the quantitative roughness analysis are the most important.
E-Mail: guo (at) pi5.physik.uni-stuttgart.de
Room: 1.934 Tel.: 64862
Optical pumping allows to probe atomic phenomena such as resonant light absorption, nuclear spin energy levels, Zeemann splitting and Rabi oscillations. The fundamental idea of optical pumping is to use polarized light to create an energy population distribution that is different from the Boltzmann distribution at a given temperature. In the experimental setup gaseous Rubidium is pumped, which has a hydrogen-like electronic configuration but consists of two isotopes with different nuclear spins leading to manifold lines.
E-Mail: m.schmid (at) pi4.uni-stuttgart.de
Room: 1.543 Tel.: 64867
In this students’ lab a simple He-Ne-Laser is aligned for different output mirrors.The stability ranges for different resonator arrangements and the laser gain are determined. Also the axial development of the laser beam is visualized by a CCD camera and will be measured. By different frequency selective optical elements inside the resonator the laser is operated at different wavelength. The output wavelength is thereby determined by a CCD spectrometer. The axial modes of a He-Ne-Laser will be examined with a Fabry-Pérot-Interferometer. Key words Laser conditions, laser types, 2-,3-,4- level laser, stimulated and spontaneous emission, absorption, line broadening mechanism, laser modes, free spectral range, finesse, axial and transversal modes, Fabry-Pérot-Interferometer.
E-Mail: j.defrance (at) pi4.uni-stuttgart.de
Room: 1.939 Tel.: 64864
In a measurement, the demanded information is often given in a time-dependent voltage signal, in the so called time domain. With an oscilloscope, you can record these signals. However, the desired information is often coded in frequency, so one is only interested in particular frequencies. With the aid of a spectrum analyser, the desired signals can be visualized in the frequency domain. Using examples of simple physical experiments (acoustic resonator, coupled oscillator, fluxgate magnetometer), the experiment demonstrates the versatile possibilities of Fourier methods. Where the oscilloscope just detects noise, you can detect signals in the Fourier space, which differ in amplitude by a factor of 10.000. Aside, a spectrum analyser is excellently qualified for analysing amplitude- or frequency-modulated signals or for the characterisation of nonlinearities.