Experiments during Sommersemester 2021
E-Mail: P.Radhakrishnan (at) fkf.mpg.de
Room: 1.570 Tel.: 64849
A better understanding of material properties allows us to manipulate them and create new compounds with better electronic, mechanic and optical properties. However such an understanding requires the knowledge of the detailed structure of the materials, because without this knowledge one is as lost as in unknown territory without a map. With X-ray diffraction structural parameters of crystalline materials can be determined with high precision. In this experiment the basic principles of X-ray diffraction are developed. For this purpose in the first part of the experiment the properties of X-rays and their absorption characteristics are investigated with an X-ray apparatus. In the second part the structural properties and parameters of single crystals are determined with X-ray diffraction.
Generation and absorption of X-rays, crystalline structure, lattice, reciprocal lattice, Bragg reflection, Laue equations, X-ray tubes, counter tube, Compton effect, x-ray fluorescence.
E-Mail: rukmani.bai (at) itp3.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: gardi (at) is.mpg.de
Room: 1.519 Tel.: 64813
Today nuclear magnetic resonance (NMR) is one of the most important spectroscopic methods in physics, chemistry, biology and medicine. It provides information about the electronic environment of single atoms and their interactions with neighbouring atoms. This information allows the analysis of the structure and dynamic of the sample. The measuring principle of cw- and pulsed NMR is shown with a simple spectrometer. The characteristic values T1 (spin-lattice relaxation time) and T2 (spin-spin relaxation time) are determined for selected samples.
classical and quantum mechanical description of nuclear magnetic resonance, pulse-NMR (rotating coordinate system, FID, spin echo, pulse sequences), measurement of T1 and T2 (spin-spin relaxation, spin-lattice relaxation)
E-Mail: v.vorobyov (at) pi3.uni-stuttgart.de
Room: 1.921 Tel.: 64876
Noise ultimately determines the sensitivity limit in all physical measurements. There is no measuring system that is free of statistical fluctuations. In measurements of current and voltage this fluctuations originate from the finite size of the elementary electric charge (shot noise) or the thermal motion of the charge carriers (thermal noise). An exact noise analysis thus allows the precise measurement of the elementary electric charge e- and the Boltzmann constant kB. Therefore in this experiment noise itself is the investigated signal.
E-Mail: skalavi (at) fmq.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: kng (at) pi5.physik.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: anasuri (at) pi5.physik.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.