The investigations of free atoms, molecules, clusters and nanomaterials, but also various gases and liquids
In order to understand the interaction of radiation with matter and the structure of solids at a microscopic level the starting point is to study single atoms and molecules. The investigation of these relatively simple systems can provide information that can be utilized to gain insight into more complex systems such as macromolecules, adsorbates, clusters, solids and their interfaces.
Gas-phase atmospheric molecules, organic molecules of biological relevance, nano- and industrial materials are subjected to the ionizing radiation from the sun, cosmic rays and natural or artificial X- and g-ray sources. Ultraviolet radiation changes the molecular electronic structure, causing the dissociation of molecules to free radicals. These free radicals can interact with other molecules via chemical reactions, causing, for example, ozone depletion. The interaction of an X-ray with a biological matter leads to a multiple ionization of molecules, which causes a radiation damage. Such X-ray damage is a root cause of cancerous processes and mutations in living cells. The fragmentation processes caused by radiation are responsible for the degradation of materials. Since it is difficult to study molecular dissociation reactions in a normal condition, for example the upper parts of the atmosphere, they must be studied in laboratory conditions. The ultraviolet radiation from synchrotron radiation sources can be used to simulate the solar radiation when studying atmospheric and biological molecules. In order to understand the fragmentation pathways, investigations the using of photoelectron spectroscopy and photoelectron photoion coincidence spectroscopy of single molecules would be proper.
A rapid development has recently taken place in semiconductor and nano-manufacturing technologies as well as in setting the demands on the development of the quality and quantity of the industrial methods of processing and refining metals. To improve the properties of nanomaterials it is important to understand the electronic structure at a microscopic level, starting from the atomic building blocks of the matter. The band structure of a material is the key to predict and describe the macroscopic properties of materials, such as metallicity, luminous properties, magnetism, etc. The use of synchrotron radiation at various photon energies, from a simulated sunlight emission to X-ray, the induced core shell phenomena form an essential part of the research.
Photo luminescence investigations of band structure
Band structure of materials will determine its properties. In order to predict the properties of different functional materials and to develop novel devices, intensive investigation of luminescent materials is needed in order to improve our life style.
Luminescent materials, also called phosphors, are used to convert different forms of energy to light. These materials have been in the focus of many research groups for decades and now can be found in many every-day applications, such as lamps and displays. In order to develop more efficient and environment friendly devices, full understanding of energy level structures in a solid material has to be gained. A powerful tool for studying the energy level structure, besides electron spectroscopy, is a luminescence spectroscopy using monochromatized synchrotron radiation.
The investigations of surfaces and interfaces under UHV condition
The surface, the outermost layers of the solid and the interface, the boundary between the two phases or matter, are important subjects of physics and chemistry, since in many cases they determine the performance of devices. For example, a better understanding of catalysis, semiconductor electronics devices, super-capacitors, energy storage and producer devices are needed in order to improve their performance and thus our lifestyle.
Room-temperature ionic liquids (RTIL) are the most promising electrolytes for improving the safety of Li-metal batteries and electrochemical double-layer capacitors (EDLC), which could be important for developing an electrical energy source with higher energy densities, applied for example, in transportation applications. Recent research activity of ionic liquids has created interest in the chemical composition of the interface between ionic liquids and a solid electrode surface composed of a metal or carbon (including nanoporous carbon-based electrodes). In order to enhance EDCLs it is important to investigate the processes occurring at the interface in situ under the device working condition. A good tool to probe the changes in the electronic structure is the valence and core-level photoemission.
Important subjects of investigation are the synthesis and investigation of nanopatterned multifunctional surfaces with the aim of developing advanced metal alloys. The aim is to create a generic template for effecting novel functionalities (e.g. surface-mediated biotin-avidin technologies, supra-omniphobicity and novel solid-solid interfaces) via nanomolecular monolayers.
The selectivity, geometry and areal density of the silane bilayer can be controlled by substrate nanopatterning and by selection of functional silane groups. The achieving of these surfaces is highly challenging due to the wide range of materials (solids and soft-matter) and size regimes (from atoms to proteins). The investigations with ex situ samples require sample loading facilities and a high-volume/high-throughput electron spectroscopy (XPS, XAS) instrumentation. STXM and PEEM facilities at MAX IV will readily complement these techniques. The relevant applications are being used already in biosensor technology (avidin-biotin technology), enzyme catalysis, adhesion technologies and anti-biofouling coatings.