Experiments during Sommersemester 2019
E-Mail: hh.kim (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 and crystalline powder are determined with X-ray diffraction.
Generation and absorption of X-rays, crystalline structure, lattice, reciprocal lattice, Bragg reflection, Laue equations, Debye-Scherrer diagrams, X-ray tubes, counter tube
E-Mail: G.Kim (at) fkf.mpg.de
Room: 1.535 Tel.:
When light hits matter it gets scattered. Mostly this happens in form of elastics scattering (Rayleigh scattering), where the molecule almost instantly reemits the entire absorbed photon energy with the same frequency. However the excited molecule can absorb (or emit) a (small) part of the photon energy e.g. as molecular vibrations and emit light with a smaller (or larger) frequency. This is called Raman-scattering. The Raman spectrum is characteristic for each molecule and each crystal. From the energy difference to the incident light and the polarization degree of the scattered light and with the help of group theory one can gain informtation on the atomic structure of the samples. The selection rules for Raman- and IR spectroscopy differ in a way that both methods complement each other very well. In the experiment the Raman spectra of CHCl3, CHBr3, CdCl3 und CdBr3 are measured. In the setup the light from a HeNe-Laser scattered off the sample is analyzed with a spectrometer. For the evaluation the measured Raman spectra are compared for these molecules with group theory and assigned to their corresponding group. The Boltzmannn contstant is determined from the intensity ratio between Stokes- and Antistokes lines. Keywords: Raman transitions (Stokes and Antistokes), vibrational spectroscopy, group theory of simple symmetries
E-Mail: til.ullmann (at) igvp.uni-stuttgart.de
Room: PI 218 Tel.: 2480
Over 99% of visible matter in the universe exists in plasma state. On earth natural occurring plasmas are only found in the upper layers of our atmosphere or in natural lightnings. First since the 1920s the research group of Irving Langmuir has devoted themselves to the scientific investigation of plasmas that were generated in the laboratory. Langmuir coined the term “plasma”. In this experiment the work with one of the most important diagnostic tools in plasma physics, the Langmuir-probe, is learned. Two different types of probes are used, the single and the double probe, in order to study the plasma parameters of a glow discharge dependent on different discharge parameters. With the Langmuir-probe a number of fundamental properties of a plasma that distinguish it from the other states of matter can be illustrated.
E-Mail: P.Radhakrishnan (at) fkf.mpg.de
Room: 1.919 Tel.: 64875
Mass spectrometry is one of the most important physical investigation methods in physics, environmental analysis, chemistry and industrial process monitoring. In mass spectrometry the atomic and molecular mass composition (m/e-ratio) of a sample is measured. In the experiment a quadrupole mass spectrometer is used to analyze samples qualitatively and quantitatively. The natural isotope ratio of krypton is investigated, also breathing air and several known organic solvents. Furthermore an unknown substance has to be identified by means of the fragmentation pattern. Keywords: setup and theory of different types of mass spectrometers, ion sources, isotopes, generation and measurement of ultra-high vacuum, vacuum pumps (rotary vane pump, turbomolecular pump), vacuum gauge (Pirani and Penning vacuum meter)
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: s.upendar (at) pi4.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.