[1] Norwegian Univ Sci & Technol NTNU, Dept Phys, N-7491 Trondheim, Norway
[2] Univ Oslo, Dept Phys, N-0316 Oslo, Norway
[3] SINTEF Mat & Chem, Dept Synth & Properties, N-7491 Trondheim, Norway
[4] Univ Poitiers, CNRS, UPR 3346, Inst Pprime,SP2MI, F-86962 Chasseneuil, France
[5] Norwegian Univ Sci & Technol NTNU, Dept Mat Sci & Engn, N-7491 Trondheim, Norway