[1] Univ Fed Mato Grosso, Dept Fis, Cuiaba, Brazil
[2] Univ La Frontera, Dept Ciencias Fis, Casilla 54D, Temuco, Chile
[3] Univ Magdalena, Fac Ingn, Santa Marta, Colombia
[4] Univ Tarapaca, Inst Alta Invest, Casilla 7D, Arica, Chile
[5] Univ Nacl Colombia, Dept Fis, Bogota, Colombia
[6] Fdn Researchers Sci & Technol Mat, Bucaramanga, Colombia
[7] Escuela Super Empresa Ingn & Tecnol, Bogota, Colombia