Presentation Information

[24a-P01-10]Gold Nanodisk Pattern Controls the Arc-like Distribution of Gold Nanoparticles: Optical Binding outside the Trapping Laser Beam

〇(M2)Mu-En Li1, Chin-Hao Huang1, Xu Shi2, Kosei Ueno2, Boris Louis3, Roger Bresoli-Obach4, Johan Hofkens3, Hiroaki Misawa1,2, Hiroshi Masuhara1 (1.Nat'l Yang Ming Chiao Tung Univ., Taiwan, 2.Hokkaido Univ., Japan, 3.Ktholieke Univ. Leuven, Belgium, 4.Univ. Ramon Llull, Spain)


optical trapping,optical binding,lithography-fabricated pattern

The precise single particle manipulation through optical trapping is a promising technique to investigate individual particle phenomena and large assembly behavior. In our previous work, we reported a large dumbbell-shaped assembly of gold (Au) nanoparticles (NPs) at the glass/solution interface, which we named swarming.1 It is constructed by optical binding inside and outside the focal spot.2 For the purpose of understanding optical binding outside the irradiation area, we introduced electron beam lithography- fabricated Au nanodisk pattern, mimicking the optical binding of Au NPs.3 The aim of this work is to consider the role of the central alignment of Au NPs in the swarming by employing an artificial structure.
Regarding the investigation at single particle-level, when circularly polarized laser is introduced, the trapped Au NP is not located at the center of laser focus; instead, a small 3-D shift is observed. We expand this phenomenon into ensembled level, the arc-like distribution of the uni-directional swarming emerges through averaging the intensity of each frame (Fig. 1). It is worth mentioning that this arc-like distribution has not been observed in the absence of the nanodisk. Moreover, the arc-like distribution with half-wavelength periodicity indicates the optical binding behavior outside the irradiation region.2 On the basis of these results, we propose that nanodisk has an indispensable role in suppressing the rearrangement of the central Au NP alignment, stabilizing an antenna-like structure inside the trapping laser beam, and further enhancing the scattered field outside the irradiation area.