1. Department of Physics and Interdepartmental Centre NanoMates University of Salerno via Giovanni Paolo II, Fisciano Salerno 84084 Italy
2. CNR‐SPIN via Giovanni Paolo II, Fisciano Salerno 84084 Italy
3. Department of Physical and Chemical Science University of L'Aquila Via Vetoio, Coppito 67100 L'Aquila Italy
4. CNR‐SPIN L'Aquila Via Vetoio, Coppito 67100 L'Aquila Italy
5. Department of Chemistry University of Manchester Manchester M13 9PL UK