Topic outline

  • Detailed instructions and video demonstrations for the exercises are available on section "Materials"

    1. Boiling phenomena

    Assistant: Marco Marin Suarez

    This laboratory exercise demonstrates heat transfer and different boiling modes. Concepts like heat flux and heat transfer coefficient are utilized to determine a boiling curve and critical heat flux. Boiling heat transfer is an important process in energy technology, for example in boiling water reactors, heat exchangers and centralised solar collectors.

    2. Photonic Bandgap Materials

    Assistant: Mohammad Tasnimul Haque mohammad.haque(ät)
    Photonic bandgaps occur in materials where the structure of the material causes constructive and destructive interference of the scattered light. Scattering accompanied with interference behaviour is called diffraction. Some examples of photonic bandgap (PBG) materials found in nature are the vivid colours of the eye in a peacock feather, the green iridescent colour of certain beetles, the blue colour of certain butterflies and the colours of the mineral opal. In this exercise, optical properties of colloidal crystal samples are investigated with a spectrophotometer and an optical microscope.

    3. Quantization of conductance in nanowires

    Assistant: Marie-Melody Volard marie-melody.volard(ät)

    This laboratory work gives you a chance to experimentally observe quantization steps in conductance. Nanowires can be obtained by placing in contact two metals of any size and then separating them. At the last stages of the breakage of the macroscopic contact the contact has nanometric size and nanowires form between the two macroscopic metallic objects brought together. In the work you will test a conductance of a loose electrical contact formed between two thin gold wires and determine the value of the conductance quantum.

    4. Synthesis and measurement of carbon nanotubes

    Assistant: Qiang Zhang qiang.zhang(ät)

    Carbon nanotubes are long hollow cylindrical nanostructures comprised solely of carbon atoms. Most of the fascination with this material, and many of its unique properties, stems from its unusual structure and aspect ratio. They can be considered as quasi one-dimensional systems, and exhibit unusual electrical and mechanical properties. In this exercise carbon nanotubes are synthesized and their properties are determined using absorption spectra and Raman spectrometer.

    5. Surface state dispersion of copper with STM

    Assistant: Markus Aapro markus.aapro(ät) and Xin Huang xin.huang(ät)

    This assignment introduces low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS) that are able to provide structural and electrical information of surfaces with atomic spatial resolution. These techniques will be illustrated by imaging Cu(111) surface and measuring the dispersion of the two-dimensional free electron gas (surface state) present on the surface. This can be achieved by measuring the oscillations in the local density of states arising from the scattering of the surface state off surface impurities.

    6. Superconducting niobium cavity

    Assistant: Mika Sillanpää mika.sillanpaa(ät)

    The most prominent consequence of superconductivity is the disappearance of electrical resistance at temperatures below the superconducting transition temperature, also known as the critical temperature Tc. However, at temperatures only somewhat below Tc, remaining normal-conducting electrons can cause observable resistive ("Ohmic") losses when time-dependent electromagnetic fields are present. In this assignment, we will measure energy losses in a superconducting microwave-frequency cavity resonator at temperatures down to 4 K by dunking it into liquid helium in a test cryostat. The measurement range crosses Tc ~ 8 K of niobium, hence allowing for inferring a temperature-dependent surface resistance of the superconductor. Meanwhile, we study concepts in radio/microwave technology, and in cryogenics.