Characterization of magnetic nanoparticles in solution is challenging due to the interplay between magnetic relaxation and agglomeration. The AC magnetic susceptibility of magnetite nanoparticles in water has been studied using magneto-optical methods in the frequency range of 10 Hz–250 kHz. The Faraday effect is detected simultaneously with changes in the fluid configuration. It is shown that the relative sensitivity to the magnetic and structural response can be adjusted by varying the wavelength, paving the way toward spatially resolved studies at the micro-scale.Characterization of magnetic nanoparticles in solution is challenging due to the interplay between magnetic relaxation and agglomeration. The AC magnetic susceptibility of magnetite nanoparticles in water has been studied using magneto-optical methods in the frequency range of 10 Hz–250 kHz. The Faraday effect is detected simultaneously with changes in the fluid configuration. It is shown that the relative sensitivity to the magnetic and structural response can be adjusted by varying the wavelength, paving the way toward spatially resolved studies at the micro-scale.

中文翻译：

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磁铁矿纳米粒子交流磁化率的宽带光学测量

由于磁弛豫和团聚之间的相互作用，溶液中磁性纳米颗粒的表征具有挑战性。已使用磁光方法在 10 Hz–250 kHz 的频率范围内研究了水中磁铁矿纳米粒子的交流磁化率。法拉第效应与流体配置的变化同时被检测到。结果表明，可以通过改变波长来调整对磁和结构响应的相对敏感性，为微观尺度的空间分辨研究铺平了道路。由于磁弛豫和结构之间的相互作用，磁性纳米粒子在溶液中的表征具有挑战性。聚集。已使用磁光方法在 10 Hz–250 kHz 的频率范围内研究了水中磁铁矿纳米粒子的交流磁化率。法拉第效应与流体配置的变化同时被检测到。结果表明，可以通过改变波长来调整对磁性和结构响应的相对敏感性，为在微观尺度上进行空间分辨研究铺平了道路。