Experiments

• Experiments in our course:
• Luminous phenomena: fluorescence in everyday life
• The photo blue bottle system: a model for photosynthesis
• Spiropyran: switching with light
• Organic LEDs / organic photovoltaic cells: electricity and light

Light and color have always fascinated people. Science and technology use the interaction of light and matter in many ways. Modern curved displays of mobile phones or computer monitors are only possible thanks to organic light-emitting diodes (OLEDs), fluorescence microscopy uses luminescence phenomena to make certain cell components visible. With the help of photocatalysis, chemical reactions are activated with light, following the example of nature (photosynthesis), or electrical current is generated with the help of organic polymers. Self-tinting eyeglasses, electrically switchable coloured glass panes or nano machines are applications of molecular switches.

In this online course, participants learn about some important modern applications of photochemistry based on well-known observations and illustrative experiments. After a short introduction to the basics of light and color, the structural principles of fluorescent molecules from everyday life are worked out to be able to understand applications such as fluorescence microscopy or the function of OLEDs. Subsequently, experiments on two photochemical model systems, the photocatalytically effective photo blue bottle system and the light-switchable spiropyran/merocyanine system, are used to illustrate the functioning of photocatalysts and molecular switches, respectively.
 

Experiments

• overview on different methods for 3D materials characterization
• physics of diffraction techniques
• remotely control an X-ray diffractometer to analyze the crystal structure of a material

The materials classes addressed in this course are semiconductors and metals. Characterization techniques cover 3D (tomographic) imaging and diffraction. Particularly, X-ray diffraction in Bragg-Brentano geometry for single crystalline and polycrystalline materials is introduced. The participants measure crystallographic data of single crystalline materials using remotely controlled X-ray diffractometers. A brief introduction to Miller indices allows a quantitative evaluation of the measurements.

Participants should be familiar with fundamentals of diffraction and interference. X-ray diffraction and crystallography will be introduced in the course / webinar.

Experiments

• Lithium-ion battery
• Redox flow battery
• Electrolysis of water
• Fuel cells

In our modern world, energy storage devices are becoming more and more important. Not only smartphones and tablets need batteries that are as small and light as possible. For electric cars, the batteries should be light, too, and still store high amounts of energy. Currently, the most powerful rechargeable battery type is the lithium-ion battery. Because it has high energy densities, it is particularly well suited for electromobility.
Furthermore, if we want to do without fossil fuels in Germany in the future, we will have to cover most of our energy needs with wind and solar power. However, what happens if the sun does not shine, and the wind does not blow? For these periods, energy must be stored as efficiently as possible during times when more energy is generated than consumed. In addition to lithium-ion accumulators, so-called redox flow batteries are also suitable for storing energy in solar and wind farms.
The "energy surplus" of wind and solar farms could be used to produce hydrogen as well. Hydrogen can be used as a fuel for electromobility, but also in electricity generation. The direct conversion of chemical energy (hydrogen) into electrical energy (electricity) is possible using fuel cells. 
This online course will provide insights into the function of modern energy storage systems and their applications. The theoretical explanations are supplemented by videos of experiments. Advantages and disadvantages of the different technologies are discussed with the participants.

Knowledge of redox reactions, galvanic elements, electrolysis, and standard potentials is required.

Experiments

• Thin-layer chromatography of chloroplast pigments
• Measurement of light absorption spectra of a leaf, a leaf extract and of individual pigments
• Recording of a light-response curve of photosynthesis measured as leaf CO2 uptake

Photosynthesis is without doubt the most important biological process on earth. It is essential to the planet’s ecology, biodiversity, and climate. Plants and algae convert the sun’s light energy to chemical energy stored in biomass, fruits, and seeds, providing the basis for human nutrition, shelter, clothing, and energy, and shaping the landscapes we inhabit. 
Understanding how photosynthesis works and is controlled by light intensity requires knowledge of the functions of the various pigments involved, and of the process of carbon dioxide uptake and reduction.
Thin-layer chromatography results and absorption spectra will be related to molecular structures and specific functions of chlorophyll in light harvesting, excitation energy transfer, and charge separation. The role of carotenoids in dissipation of excess excitation energy, regulation of reaction center energy supply, and prevention of oxidative stress will be considered.

Experiments

• Observation of the swimming behavior of the fish
• Recording of the electrical signal with the oscilloscope
• Perception determines behavior: simple stimulus experiments

Recording of electric signals (postsynaptic and action potentials) of nerve cells can only be carried out with quite an effort, since it is usually done intracellularly. The electrical signals of the elephant fish (Gnathonemus petersii) are more easy to investigate because they can be recorded extracellularly while the fish is allowed to swim freely. The fish uses these repetitively generated signals for orientation, not for signal transmission within its body and therefore sends them into the surrounding water.
In this digital course, the participants observe the fish and its signals live and work out the cellular processes of signal generation by comparing model electrocytes and nerve cells.
In another experiment, selected stimuli are presented to the fish and the resulting changes in the signal frequency are recorded and analyzed with a suitable documentation program. The students can evaluate which kind of stimulus has impact on the signaling and behavior of the fish.