The numerical simulation of field enhancement in near-field scanning Raman microscopy

Yaqin Li; Shifa Wu; Guoshu Jian; Kun Liu

doi:10.1117/12.575727

9 February 2005 The numerical simulation of field enhancement in near-field scanning Raman microscopy

Yaqin Li, Shifa Wu, Guoshu Jian, Kun Liu

Proceedings Volume 5635, Nanophotonics, Nanostructure, and Nanometrology; (2005) https://doi.org/10.1117/12.575727
Event: Photonics Asia, 2004, Beijing, China

Abstract

The combination of plasmon near-field scanning optical microscopy (PNSOM) and Raman spectroscopy named Near-field Scanning Raman Microscopy (SNRM) provides not only surface topography information but also chemical structural information of sample with nanometer spatial resolution, which are very important for a wide range of applications, such as the study of liquid sample, nanometer film sample, quantum dot, single molecules of biological samples and so on. But Raman scattering cross-section is too small to get Raman signal of nanometer structure, and surface enhancement Raman scattering (SERS) effect is the main technique to solve this problem. Local electric field distribution and the form of the hot spots are evaluated by the FDTD (finite difference time domain) method in SERS with respect to many kinds of models. As a result in this paper, (1) vast Raman enhancement factor of 10¹⁵ was obtained around the junction between the Ag ball (tip) and the Ag thin film (sample stage). (2) The enormous large electric field at the hot spots rapidly decays with increasing gap between the Ag ball and Ag thin film. In the process, we use the equivalent incident wave method to deal with the incident evanescent wave problem and a frequency-dependent finite-difference time-domain formulation ((FD)² TD) to deal with the negative permittivity of Ag, and the validity of these two methods have been approved by references

Citation Download Citation

Yaqin Li, Shifa Wu, Guoshu Jian, and Kun Liu "The numerical simulation of field enhancement in near-field scanning Raman microscopy", Proc. SPIE 5635, Nanophotonics, Nanostructure, and Nanometrology, (9 February 2005); https://doi.org/10.1117/12.575727

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