Plasmonic nanostructures, which allow light focusing at the deep subwavelength scale, and colloidal nanoparticles with unique optoelectronic properties are nowadays fabricated with nanometer precision. However, to fully control and exploit nanoscale light–matter interactions in hybrid plasmonic–nanophotonic devices, both materials must be assembled in heterostructures with similar precision. Near-field optical forces have recently attracted much attention, as they can precisely trap and position nanoparticles at plasmonic hotspots. However, long-range attraction and the surface bonding of nanoparticles usually require other specific techniques, such as electrothermal heating and surface chemical treatments. This Letter reports on the optical trapping and deposition of dye–molecule nanoparticles in the nanogap of a gold antenna. The nanoparticles are captured by focusing a near-infrared laser beam on a targeted plasmonic antenna. This single-step deposition process requires only a few seconds under 1.4–1.8 MW·cm –2 continuous-wave illumination and shows a polarization dependence smaller than expected. Fluorescence and electronic microscopy observations suggest that nanoparticle deposition arises from a trade-off between optical and thermal effects.

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Summar y Unintentional formation of polychlorinated biphenyl (PCB) from chemical manufacturing process of organic pigment such as phthalocyanine pigment have been known since 1976. Regarding to unintentional formed congeners in disazo pigment, in the case of 3,3＇-dichloro benzidine, PCB-11(3,3＇-), PCB-35(3,3＇,4-), PCB-77(3,3＇,4,4＇-) were dominant congeners as a result of sandmeyer reaction via its diazonium salt. On the other hand, in the case of 2, 2＇, 5, 5＇-tetrachloro benzidine, PCB-52(2,2＇,5,5＇-) , PCB-101(2,2＇,4,5,5＇-) , PCB-153(2,2＇,4,4＇,5,5＇-) were dominant congeners as a result of sandmeyer reaction via its diazonium salt. This is common in HCBz and PCB-209 existing as dominant PCB congeners in pentachloro nitrobenzene (PCNB). PCB-209 in copper phthalocyanine green and PCNB could be forming in the similar process from HCBz by radical coupling. Regarding to dioxazine violet pigment such as PV23, this pigment is synthesized by ring-closing reaction of 3-amino-N-ethylcarbazole and chloranil in o-dichlorobenzene solvent.Thermal PCB product of o-dichlorobenzene with/without Chloranil, 3-amino-N-ethyl-carbazole, radical initiator have been determined congener specifically. The dominant congeners were PCB-5(2,3-), PCB-12(3,4-), PCB-40(2,2＇,3,3＇-), PCB-56(2,3,3＇,4-), PCB-77(3,3＇,4,4＇). The formation process of these congeners were estimated via 2 types of o-dichlorobenzene radicals. We investigated experimentally unintentional formation from o-dichlorobenzene to confirm their formation process. Controlling unintentional PCB formation should be required by utilizing Best Available Technologies (BAT) and Best Environmental Practice (BEP) for environment in the case of manufacture of an organic pigment, and managing the process of chemical synthesis properly to reduce human and environmental risk.

In this work, we demonstrate an original single-nanoparticle deposition process based on near-field optical forces arising from much localized plasmonic resonant gap-mode. At first, nanoparticles exclusively made of fluorescent dye molecules are fabricated in aqueous colloidal suspension. Near-field optical forces are then used to attract and deposit single nanoparticles in the nanogap of plasmonic nanoantennas. This one-step deposition process allows targeted deposition of nanoscale materials directly from a colloidal dispersion to a few-nanometer large area of interest.