Discrete dipole approximation simulations of absorption spectra and local electric field distributions of superparamagnetic magnetite nanoparticles

作者：Wang Benyang^*; Qu Shiliang

来源：Laser Physics, 2013, 23(4): 045901.

DOI：10.1088/1054-660X/23/4/045901

The absorption spectra and local electric fields of nanosized superparamagnetic magnetites of four different shapes including a sphere, cube, cylinder and disk have been calculated using the discrete dipole approximation. The absorption efficiency and its peak position for the magnetite are dependent upon the morphology, geometry, particle orientation and ambient refractive index n. The calculation results indicate that the absorption efficiency increases with an increase in particle size, and the absorption peaks are red-shifted as the refractive index increases. The influence of size on the peak position is weak for nanospheres and nanocubes. In addition, for nanocylinders and nanodisks, increase of the aspect ratio results in a blue shift for the transverse mode (TM) and a red shift for the longitudinal mode (LM). From the TM to the LM, the peaks are blue-shifted for nanodisks, while being red-shifted for nanocylinders. Furthermore, the data curves of vertical bar E vertical bar/vertical bar E-0 vertical bar(max) and vertical bar E vertical bar/vertical bar E-0 vertical bar(min) maintain a nearly opposite trend to each other as the photon energy increases. It is notable that vertical bar E vertical bar/vertical bar E-0 vertical bar(max) shows a similar behavior to the real part of the dielectric function of magnetite bulk material. This feature can be attributed to the dielectric properties of this material.

• 出版日期2013-4
• 单位哈尔滨工业大学