1. Chemistry Institute, São Paulo State University─UNESP, Rua Francisco Degni 55, Araraquara, São Paulo14800-900, Brazil
2. Centre de Optique, Photonique et Laser─COPL─Universite Laval, 2375 rue de la Terrase, QuebecG1V 0A6, Canada
3. São Carlos Institute of Physics, University of São Paulo, P.O. Box 369, São Carlos13560-970, São Paulo, Brazil