1. Laboratorio de Bajas Temperaturas, Departamento Física de la Materia Condensada, C-III Universidad Autónoma de Madrid, 28049 Madrid, Spain, South Bank University, School of EEIE, 103 Borough Road, London SE1 OAA, U.K., Institute of Physical Energetics, 21 Aizkraules Strasse, Riga LV 1006, Latvia, and Latvian Institute of Organic Synthesis, 21 Aizkraules Strasse, Riga LV 1006, Latvia