1. Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
2. Molecular Spectroscopy Group, Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium
3. Istituto Ricerche Solari Locarno (IRSOL), Università della Svizzera italiana (USI), 6605 Locarno-Monti, Switzerland
4. Département de Chimie Physique, Université de Genève, 1211 Geneva 4, Switzerland