講演情報
[20p-A601-7]Plasmonic trapping-induced chiral crystallization of ethylenediamine sulfate with structured light
〇AnChieh Cheng1, Teruki Sugiyama2, Keiji Sasaki1 (1.Hokkaido Univ., 2.NYCU)
キーワード：
Helical optical force、enantioselectivity
The localized surface plasmon resonance (LSPR) of metal nanostructures remarkably enhances and confines the electric field in a nanoscale, enabling optical manipulation of smaller targets beyond the diffraction limit. Additionally, by designing metal nanostructure, LSPR can control the angular momentum of the confined electric field. When circularly polarized (CP) Gaussian laser beam is irradiated onto a gold triangle trimer nanostructure (GTTN), spin-orbital coupling occurs on the nanostructure, leading to the orbital rotation of a nanoscale target. Moreover, when a Laguerre-Gaussian (LG) laser beam is irradiated onto the GTTN, the direction of both the spin and orbital angular momentum in the nanogap of GTTN is reversed due to the additional orbital angular momentum. In this presentation, we demonstrate the plasmonic trapping-induced chiral crystallization of ethylenediamine sulfate. The enantioselectivity experiment involved using a CP (r-CP or l-CP) Gaussian beam or a LG beam with right- or left-handed helical wavefronts (l: ±1; r-OV or l-OV). The crystallization experiments were repeated for each condition, and the crystal enantiomeric excess (CEE) values were evaluated based on the results using the formula: (number of d-form generations – number of l-form generations)/(total number of obtained crystals)×100(%). While the excitation using a r-CP or l-CP Gaussian beam generated significant imbalance between both enantiomorph, resulting in a maximum CEE value of 44%. Intriguingly, under irradiation of same handedness LG beam reversed the dominant enantiomorph while retaining CEE of 44%. And the opposite handedness composition of LG beam shown no enantioselectivity. The presentation will discuss possible mechanisms for this unique enantioselective crystallization achieved by plasmonic trapping from the viewpoint of the interactions between crystal conformation and the angular momentum on the GTTN according to different laser beams.