title: Optical and Magnetic Properties of Fe Nanoparticles Fabricated by Femtosecond Laser Ablation in Organic and Inorganic Solvents.
abstract: Magnetic nanoparticles have attracted much interest due to their broad applications in biomedicine and pollutant remediation. In this work, the optical, magnetic, and structural characteristics of colloids produced by ultrashort pulsed laser ablation of a solid Fe target were studied in four different media: HPLC water, an aqueous solution of trisodium citrate, acetone, and ethanol. Optical extinction spectroscopy revealed an absorption band in the UV region for all, in contrast to the results obtained with nanosecond lasers. Micro-Raman spectroscopy showed that the samples are heterogeneous in their composition, with hematite, maghemite, and magnetite nanoparticles in all four solvents. Similar results were obtained by electron diffraction, which also found α-Fe. Magnetic properties were studied by vibrating-sample magnetometry, and showed nanoparticles in the superparamagnetic state. Under certain experimental conditions, submicrometer-sized iron oxide nanoparticles agglomerate into fractal patterns that show self-similar properties. Self-assembled annular structures on the nanometer scale were also observed and are reported for the first time.
authors.affiliation: Centro de Investigaciones Ópticas (CIOp) (CONICET La Plata-CIC-UNLP), CC3 (1897), Gonnet, La Plata, Buenos Aires, Argentina.
authors.forename: Jesica M J
authors.initials: JMJ
authors.lastname: Santillán
authors.affiliation: Centro de Investigaciones Ópticas (CIOp) (CONICET La Plata-CIC-UNLP), CC3 (1897), Gonnet, La Plata, Buenos Aires, Argentina.
authors.forename: David
authors.initials: D
authors.lastname: Muñetón Arboleda
authors.affiliation: Instituto de Física La Plata (IFLP), CONICET, Calle 49 y 115, 1900, La Plata, Buenos Aires, Argentina.|Departamento de Física, Facultad de Ciencias Exactas, UNLP, Calle 49 y 115, 1900, La Plata, Buenos Aires, Argentina.
authors.forename: Diego F
authors.initials: DF
authors.lastname: Coral
authors.affiliation: Instituto de Física La Plata (IFLP), CONICET, Calle 49 y 115, 1900, La Plata, Buenos Aires, Argentina.|Departamento de Física, Facultad de Ciencias Exactas, UNLP, Calle 49 y 115, 1900, La Plata, Buenos Aires, Argentina.
authors.forename: Marcela B
authors.initials: MB
authors.lastname: Fernández van Raap
authors.affiliation: Centro de Ciências Naturais e Humanas (CCNH), Universidade Federal do ABC, Avenida dos Estados, 5001, Santa Terezinha, CEP 09210-580, Santo André-Sao Paulo, Brazil.
authors.forename: Diego
authors.initials: D
authors.lastname: Muraca
authors.affiliation: Centro de Investigaciones Ópticas (CIOp) (CONICET La Plata-CIC-UNLP), CC3 (1897), Gonnet, La Plata, Buenos Aires, Argentina.|Departamento de Ciencias Básicas, Facultad de Ingeniería, UNLP, Calle 1 y 47, 1900, La Plata, Buenos Aires, Argentina.
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Schinca
authors.affiliation: Centro de Investigaciones Ópticas (CIOp) (CONICET La Plata-CIC-UNLP), CC3 (1897), Gonnet, La Plata, Buenos Aires, Argentina.|Departamento de Ciencias Básicas, Facultad de Ingeniería, UNLP, Calle 1 y 47, 1900, La Plata, Buenos Aires, Argentina.
authors.forename: Lucía B
authors.initials: LB
authors.lastname: Scaffardi
keywords: fractals; iron; laser ablation; magnetic properties; nanoparticles