The research area of matter and materials is at the core of our understanding of the physical nature of the universe and the materials and technology around us. It encompasses all length scales known to exist, from the enormous large-scale structure of the universe, via the familiar scale of meters to millimeters that form our daily life, down to the tiniest elementary particles ever observed. As such, scientific study of matter and materials is of profound fundamental and practical interest.
Study of elementary particles (EP) addresses fundamental science questions: What are the basic building blocks of matter and how do they interact? What are the building blocks of the unknown - dark matter and dark energy?
The worldwide research leadership in elementary particle physics is currently at the European Centre for Particle Physics CERN, where the world's largest particle accelerator Large Hadron Collider (LHC) is located.
The experimental research is performed in the context experiments at the LHC: The Compact Muon Solenoid (CMS), TOTEM and ALICE. CMS is one of the two general purpose experiments at the LHC, and is the flagship experiment of Finnish particle physics. The CMS team in the University of Helsinki is investigating in particular Higgs bosons, jet physics and physics of heavy quarks. The team participating in the smaller TOTEM experiment is investigating the proton structure. The team in ALICE (also contributing to CDF and MOEDAL experiments) concentrates on studies of the space-time structure of high energy hadron collisions. These teams also have vibrant interdisciplinary contacts with some of the other research themes included here: radiation-matter interactions and ALD.
Theoretical investigations concentrate on particle physics phenomenology and strongly interacting gauge theories. The High Energy Phenomenology in the LHC Era project in HIP, consisting of researchers from the Department of Physics and HIP, is focusing on particle physics phenomenology beyond the Standard Model of particle physics, and on the physics of strongly coupled gauge theories, in particular Quantum Chromo Dynamics. Recent highlights include for example results on possible additional scalar particles in addition to the observed 125 GeV Higgs boson, and investigations on the holographic connection between gauge field theories and gravity.
The key question addressed is how did the present large-scale structure of the Cosmos develop? The team studies theoretically the nature of the primordial perturbations and the cosmological dynamics of scalar fields, and participates in the European Space Agency cosmology satellite missions, Planck and Euclid, to shed light on this fundamental question. The cosmic microwave background (CMB) shows the structure of the early universe, from which the present large-scale structure has grown. This primordial structure was likely produced by high-energy phenomena in a process called cosmological inflation in the very early universe. By studying the details of the microwave background, also particle physics at high energies is probed.
The next satellite Euclid will be launched in 2020, and the University of Helsinki group has a key role in its data analysis and provides one of the Euclid Science Data Centers. This mission, and its data analysis in which Helsinki has a key role, will shed light on one of the most fundamental open questions of the nature of the universe: what is the origin of the acceleration of the universe: a new form of matter ‘dark energy’, deviations from Einstein’s general relativity, or some entirely new realm of physics? The research area is inherently connected to extragalactic physics. Extragalactic observations focus on understanding the co-evolution of galaxies and black holes and the role of environment on this process, using ground-based data from ESO telescopes and the data obtained by the ESA space missions, such as HST, Herschel, XMM-Newton. The team also numerically models the various physical processes that are relevant for the cosmological formation and subsequent evolution of galaxies. The key infrastructure enabling this research is the CSC supercomputer facilities.
The solar system is a giant laboratory facilitating in situ or nearby observations of matter and materials beyond the capabilities of terrestrial laboratories. The strategic focus of solar system research at the University of Helsinki is in the small solar system bodies and terrestrial planets as well as in the solar activity and its consequences in the plasma environments of the Earth and planets. Research of solar system phenomena utilizes large international observational data sets and advances in modern statistical inversion methods. This is closely linked to studies of physical properties of planets, moons and small solar system bodies. Both studies of near earth objects and solar eruptions are closely linked to the world-wide efforts to understand, forecast and mitigate the risks these pose to mankind and the modern technology-dependent society.
The solar system research has direct connections with the studies of matter in astronomy and with the materials research. The sun is a star and presently other planetary systems are being found with exceeding pace. Meteoritic samples are studied in the materials physics laboratories and X-ray observations are central to the future planetary research, in particular of planet Mercury where an X-ray instrument designed in Helsinki will arrive in 2024. Studies of solar system plasmas, in turn, have a cross-disciplinary connection with materials research for future fusion reactors.
The Department of Physics profiles in to the area of radiation-matter interactions, in particular in relation to Big Science infrastructures. This field encompasses the strengths of the Department, namely ion and synchrotron-based materials analysis and ion and nanocluster beam materials modification.
This research utilizes local infrastructures in Kumpula, as well as ESRF and other synchrotrons, the ISOLDE facility at CERN and swift heavy ion accelerators around the world. The area will be further developed to enhance the, already strong, collaboration with chemical materials synthesis and towards the use of new free-electron lasers that provide synchrotron radiation at unprecedented luminosities, improving e.g. capabilities for structural studies of biomolecules.
Radiation-matter interactions are also studied using methods of light scattering and radiation transfer in an ERC Advanced Grant project. This topic illustrates the multidisciplinary approach to studies of solar system bodies by remote observations and laboratory studies of solar system matter found on Earth or returned with spacecraft.
One of the key hurdles in developing an economically viable nuclear fusion power plant is to find materials that can withstand the enormous heat and radiation levels that emanate from the 100 million degree hot fusion plasma – which is just half a meter away from the materials. Similarly, the desire to build particle accelerators with increasingly high energies and luminosities lead to huge electric fields and currents at the materials inside the accelerator.
Slightly paradoxically, since fusion research has long been largely focused on plasma physics, and particle accelerator development on radiofrequency wave technology, the large research institutions in the fields have had weak connections to modern materials physics. The University of Helsinki has an internationally leading effort in computational and experimental research on materials response in the extreme conditions of fusion reactors such as JET in the UK and projections for ITER, and future particle accelerators such as CLIC at CERN, and FAIR.
Thin films and other nanostructured materials are needed in all fields of modern technology from microelectronics to medical applications and corrosion protection. Atomic Layer Deposition (ALD) is the fastest growing method for depositing thin films. The ALD method is of Finnish origin and the research group at Department of chemistry is in a worldwide leading position in developing ALD chemistry. The group together with the Accelerator laboratory in the Physics department forms the main part of Finnish Centre of Excellence in ALD. Also operating at the chemistry department building is an R&D laboratory of the large international company ASM Microchemistry, working in an active collaboration with the university group.
The emphasis in the ALD research has been in thin film materials needed in future generation integrated circuits that form the backbone of the computer industry but also have applications in energy technologies, optics, surface engineering and biomaterials. Other nanostructured materials being studied include nanofibers made by electrospinning and related techniques, porous materials made by anodization, ion exchange materials for treatment of radioactive waste.
The need of functional polymer materials increases steadily. The variety of such polymers is wide, ranging from conducting polymers to self-assembling aqueous polymers applicable, e.g., in drug release or diagnostic applications. Modern synthetic methods and the processability of the natural biopolymers allow the creation of polymers which self-assemble in solid state or in liquids, this making it possible to construct intelligent (nano)devices and materials.
“Smart” polymers which react to changes in temperature, pH, electric field, or light are being intensely studied, and University of Helsinki has been very active in the field. Typically, the polymers respond by changing their molecular conformations leading to changes in their volume, shape, and solubility.
Tailored nanomaterials are applicable in various future applications in the pharmaceutical field. These applications include materials for regenerative medicine, drug targeting and diagnostics. UH groups investigate nanomaterials for transplantation purposes. The materials include natural and biotechnologically produced biomaterials (e.g. collagen, laminin, nanofibrillar cellulose) and their tailored versions. Furthermore, nanomaterials are the basis for generation of miniatyrized 3D cell models for drug development and transplantation.
Drug targeting is based on hybrid materials of peptides, lipids, polymers, inorganic nanoparticles and biological components. The assembly and construction of the materials are being optimized for cell and tissue targeting or pharmaceuticals. Furthermore, the systems are designed for externally triggered drug release and visualization in the body. These studies involve various physical, chemical, computational and biological methods. Method development includes also novel approaches for label free monitoring of the materials in biological media. Printed biomaterials thin films are an emerging field of the modern biomedical- and pharmaceutical research field, which will lead to new applications of nanoparticles as drug and biomolecule (incl. cells) delivery systems, drug discovery tools and toxicity testing, diagnostics and tissue engineeringcarriers for radiotracers.
Depleting oil resources and increasing ecological awareness give requirements to replace current mineral oil based industry to utilize renewable resources with biological origin (e.g. plant, microbial). Further, many of the current production methods are in urgent need to be upgraded or replaced with more efficient, but yet environmentally benign methods. The use of plant-based biopolymers, from abundantly available wood or agrobiomass, is an excellent choice for a sustainable bio- and circular economy in future society. The components of refined biomass can be utilized directly (e.g. production of textiles or lightweight materials from unconventional, abundant sources) and green and sustainable chemical or chemo-enzymatic methods are utilized to upgrade biomass to novel materials and chemicals.
Mathematical studies of materials include analysis of thermal transport in crystalline structures, non-destructive testing and imaging of materials, metamaterials and metamaterial based cloaking, and nanomechanical systems.
Transport of matter and energy in a given physical system is a central question for practical applications. To bridge the gap from a given microscopic evolution to macroscopic phenomena one needs to cross over scales of several orders of magnitude. The mathematical physics group at University of Helsinki is one of the leading units in using renormalization group flow and scaling limits leading to intermediate transport equations, statistical field theory techniques, kinetic theory of phonons in crystal structures, turbulent transport and transport in random media.
The research in inverse methods has led to breakthroughs in understanding the metamaterials. Metamaterials are smart materials, engineered to have properties that have not yet been found in nature. The research at the University Helsinki has been particularly successful in studying metamaterial based devices (e.g. invisibility cloaks and negative refraction). Non-destructive testing and imaging of materials, metamaterials and metamaterial based cloaking are studied as inverse problems, with the general goal to recover information or image materials from indirect and noisy observations. Such questions are key issues in situations such as exploration geophysics and non-destructive testing of materials when one measures the response of the medium when probed with different kinds of waves, including X-rays, sound waves and electromagnetic waves. At the University of Helsinki, a particular focus area is the use of measurements by electrical fields or X-ray tomography to improve imaging of materials.
The study of nanomechanical systems and nanophysics in general raises fundamental questions pertaining the domain of the validity of the statistical laws of physics, which are very successful to explain phenomena at the macro and mesoscale. Concepts and methods from the study of open quantum systems are therefore equally needed as those from non-equilibrium statistical mechanics. The current research at the University of Helsinki encompasses several aspects of theoretical nanoscience. It embraces applications of classical stochastic analysis and stochastic control to non-equilibrium thermodynamics.