1. Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden, School of Marine Science and Technology, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom, Division of Mechanical Engineering, University of Dundee, Dundee DD1 4HN, United Kingdom, TNO Science and Industry, Bevesierweg MML (Harssens), Den Helder, The Netherlands, and School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom