講演情報
[18a-S4_201-5]Femtosecond laser near-field reduction of gold ions for formation of nanoplate with through-nanoholes
〇Shi Bai1, Kazunari Ozasa1, Koji Sugioka1 (1.RAP, RIKEN)
キーワード：
Femtosecond laser processing、Near-field、Laser reduction
Laser near-field processing enables ablation and modification of materials within a confined region far beyond the optical diffraction limit [1]. Thus, the nano-pattern/structure, whose dimension is much smaller than λ/2, can be fabricated on a flat target surface [2]. However, forming nano-pattern/structures on a single nanomaterial such as a nanoplate is very challenging. For example, the laser processing at the nanoscale requires sophisticated focusing systems for the extreme short wavelength. In this talk, we present a laser near-field reduction of gold ions to form through-nanoholes on gold nanoplates, in which silica microsphere are used to focus the femtosecond laser beam onto the nanoscale regions. The femtosecond laser with a 515 nm wavelength and a pulse width of 230 fs was used to reduce gold ions and form gold nuclei in the optical near-field at the bottom of silica spheres self-assembled on a silicon substrate. Sodium dodecyl sulfate (SDS) mixed in gold precursor enabled the gold nuclei grows along the substrate surface. As a result, the through-nanoholes with an average size of ~230 nm were generated on the gold nanoplates, when the femtosecond laser was focused by using 1 μm diameter silica microsphere, as shown in Fig. 1. In addition, we found sub-10 nm gap was formed at the edge of nanoplates. The presented approach provides a pathway to realize nanomodification of nanomaterials by femtosecond laser processing, which can be used for single-molecule sensing using surface-Raman scattering.
Reference:
[1] J. Boneberg et al. Opto-Electron. Sci. 1, 21003 (2022).
[2] E. McLeod et al. Nat. Nanotech. 3, 413 (2008).
Reference:
[1] J. Boneberg et al. Opto-Electron. Sci. 1, 21003 (2022).
[2] E. McLeod et al. Nat. Nanotech. 3, 413 (2008).