Bio and Environmental Physics
Physical phenomena have fundamentally quantum origin. Basic biological processes, including photosynthesis, on the other hand, typically obey classical rules. However, since photosynthesis begins with absorption of solar quanta, it can be considered at a borderline of classical and quantum realms. It is generally agreed that absorption of a solar photon by light-harvesting antenna complexes creates a coherent exciton that transfers its energy very efficiently to the photochemical reaction centre, where it is subsequently transformed into chemical energy. Yet this insight has primarily arisen from interpretation of the low-temperature spectroscopic experiments; evidence for the excitons at physiological temperatures is scarce at best. Basic experimental and theoretical studies are, therefore, carried out over broad range from cryogenic through ambient temperatures to prove the presence of photosynthetic excitons at functional conditions and to study their properties.
Principal investigator Prof Arvi Freiberg, Laboratory of Biophysics
Airborne nanoparticles and their role in meteorological processes
A key for understanding the microphysical basic processes of the weather and climate is the particle formation and growth from one nanometre up to cloud drops. Leadership in the electric mobility spectrometry of airborne nanoparticles provides a good start for the research group to understand this chain of physical processes and to develop adjusted numerical weather and climate models. The theory of nanoparticle formation and growth, a database of measurements, and advanced physical and optical models of aerosols and cloud particles will be developed. The results will be applied composing new radiative transfer blocks for numerical weather and climate models and applied in national and international environmental weather and climate programs. Studies are supported by the Estonian Science Infrastructure Roadmap Project “Estonian Environmental Observatory”, which includes corporate developing of the Estonian SMEAR station.
Principal investigator Dr Urmas Hõrrak, Laboratory of Environmental Physics
Chemical composition and interactions in atmosphere: from gases to aerosols and climate change
Principal investigator Dr Heikki Junninen, Laboratory of Environmental Physics
Radioactivity in the environment and the resulting radiation doses are, besides a national monitoring programme, objects of scientific research in all neighbouring states and cannot be neglected in Estonia as well. This is an obligation by international agreements, EURATOM treaty and corresponding legal acts, but there is also the need to provide professional information, to measure the environmental radioactivity and interpret the monitoring results, to evaluate current situation and make prognoses for future developments in the field of radiation protection, in cases of emergencies, etc. Main research is focused on the following topics. a) Environmental radioactivity research in Estonia for obtaining information about transport and migration of natural and artificial radionuclides in the soil, air and water, as well as radioecological pathways of radionuclides and the formation of irradiation dose in radioactive waste management and impact sources from energy production. b) Development and implementation of gamma-spectrometry and methods for numerical modelling, including low-energy high-purity Ge (HPGe) gamma-spectrometry, validating quality measures for quantitative analysis of environmental samples through routine international proficiency tests practice, transport models of radionuclides and radioecological models of radionuclide pathways in the air, water and soil, gamma-radiation resonance forward-scattering models of ultra fine interactions. c) Development of analysis methods for alpha- and beta-radiation detection in environmental applications.
Principal investigator Dr Madis Kiisk, Laboratory of Environmental Physics