LAUSR

Abstract Transverse magneto-optical measurements of iron oxide magnetic nanoparticles (MNPs) dispersed in water was studied by using a 532 nm laser light and a reflection cell composed of a glass prism and a shallow cell or a glass prism and a deep cell. In the shallow cell, the absorbance of the bulk phase of the dispersion was measured in the low MNPs concentration of 0.005–0.2 wt%, but in the higher concentration than 0.2 wt% the absorbance of the interface was observed predominantly. The deep cell allowed measuring the absorbance of the interface in the wide MNPs concentration range of 0.018–3 wt%. The observed absorbances were analyzed according to Langevin equation, which gave the magnetic moment of MNPs and the absorbance at the saturated magnetization of MNPs. By the present method, the interfacial adsorption of COOH modified MNPs assisted by a cationic surfactant at the glass/water interface was demonstrated.