1. Department of Applied Physics, University of Extremadura, Avda. de Elvas s/n, 06006 Badajoz, Spain
2. Department of Analytical Chemistry, University of Extremadura, Avda. de Elvas s/n, 06006 Badajoz, Spain
3. Department of Chemical Engineering and Physical-Chemistry, University of Extremadura, Avda. de Elvas s/n, 06006 Badajoz, Spain