Valeria Videtta

Spin-Polarization Transfer in Colloidal Magnetic-Plasmonic Au/Iron Oxide Hetero-nanocrystals

We report on the unprecedented direct observation of spin-polarization transfer across colloidal magneto-plasmonic Au@Fe-oxide core@shell nanocrystal heterostructures. A magnetic moment is induced into the Au domain when the magnetic shell contains a reduced Fe-oxide phase in direct contact with the noble metal. An increased hole density in the Au states suggested occurrence of a charge-transfer process concomitant to the magnetization transfer. The angular to spin magnetic moment ratio, m(orb)/m(spin), for the Au 5d states, which was found to be equal to 0.38, appeared to be unusually large when compared to previous findings. A mechanism relying on direct hybridization between the Au and Fe states at the core/shell interface is proposed to account for the observed transfer of the magnetic moment.

Selective synthesis of TiO2 nanocrystals with morphology control with the microwave-solvothermal method

In this paper, a method to synthesize anatase TiO2 nanorods by hydrolysis of titanium(IV) isopropoxide (TTIP) in the presence of benzyl alcohol and acetic acid at 210 °C was tested. The novelty of the present approach relies on the evaluation of the shape-controlled synthesis of anatase TiO2 nanocrystals via a microwave-solvothermal method in 45 min. The different TiO2 nanocrystals were obtained by tuning the TTIP/acetic acid ratio under optimized synthetic conditions and were characterized in detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), micro Raman (together with microphotoluminescence) and FT-IR spectroscopies. The acetic acid coordinated on the nanocrystal surface was removed by the reduction of its carboxyl group via a “super-hydride reaction”, and the photocatalytic activity of bare TiO2 nanocrystals, under visible light irradiation, was also evaluated: the best performing TiO2 anatase nanocrystals exhibited a discrete photoactivity, completely degrading Rhodamine B solution in five hours.