1. Atmosphere and Climate DepartmentNorwegian Institute for Air Research Kjeller Norway
2. Department of Geoscience, Meteorology and Oceanography SectionUniversity of Oslo Oslo Norway
3. SINTEF Materials and Chemistry Oslo Norway
4. Centre for Material Science and Nanotechnology, Department of ChemistryUniversity of Oslo Oslo Norway
5. Geological and Mining Engineering and SciencesMichigan Technological University Houghton Michigan USA
6. Energy Technologies Department, Optical Components GroupENEA Casaccia C.R.E Rome Italy
7. Department of Earth SciencesUniversity of Geneva Geneva Switzerland