Magnetic susceptibility measurement of single iron/cobalt carbonyl microcrystal by atmospheric magnetophoresis

Abstract

In this study, the use of an innovative atmospheric magnetophoresis, which enables us to measure the mass magnetic susceptibility and mass of a microparticle simultaneously, was demonstrated. Using this technique, we determined the magnetic susceptibility of a crystalline deposit of iron/cobalt carbonyl, mainly composed of Fe 2 (CO) 9 , which was prepared photochemically from a gaseous mixture of iron pentacarbonyl (Fe(CO) 5 ) and cobalt tricarbonyl nitrosyl (Co(CO) 3 NO). The mass magnetic susceptibility and the characteristic relaxation time of the microcrystal were (7.0 ± 1.9) × 10 −9 m 3 kg −1 and (5.6 ± 2.2) × 10 −4 s, respectively. The observed magnetic susceptibility shows that the microparticle was paramagnetic. Assuming that the density was equal to that of Fe 2 (CO) 9 (2.1 × 10 3 kg m −3 ) and that the shape of the particle was spherical, a hydrodynamic radius of 4.7 µm and a mass of 0.91 ng were observed. It was suggested that Co was incorporated in Fe 2 (CO) 9 .