Journal: ACS nano

Article Title: Sub-Diffraction-Limited Milling by an Optically Driven Single Gold Nanoparticle

doi: 10.1021/nn2023045

Figure Lengend Snippet: Optically driven golden nano-burner. a) Diagram of the experimental setup. A microscope equipped with dark-field illumination via an oil immersion condenser (Zeiss Axiotech 100) is adapted to include the manipulation laser (Millenia Vs 532nm, Spectra-Physics). An air objective (Epiplan, Zeiss, 100x, NA 0.9) is used to simultaneously collect scattered light and focus the manipulation laser onto the sample. The sample position is controlled with piezo-driven stepper motor translation stages (Linos). Images are acquired using a digital camera (Canon EOS 550D). Scattering spectra are acquired using a spectrometer (Andor SpectraPro-300i) equipped with a CCD camera (Roper Scientific 1340/400). (b) Schematic representation of the optical forces acting on a nanoparticle inside a polymer layer during the patterning process. The laser beam is focused slightly above the substrate to utilize the radial optical force component of a divergent laser beam.

Article Snippet: To demonstrate this method, we use spherical citrate-stabilized gold nanoparticles with diameters of 80 nm and 40 nm purchased from BBInternational.

Techniques: Microscopy

Journal: ACS nano

Article Title: Sub-Diffraction-Limited Milling by an Optically Driven Single Gold Nanoparticle

doi: 10.1021/nn2023045

Figure Lengend Snippet: Sub-diffraction-limited milling by a nano-burner. Nano-channels milled in a PVA layer by a single optically driven gold nanoparticle of (a) 40 nm and (b) 80 nm diameter. Both dark-field microscopy (left) and atomic force microscopy (right) images are present. The white arrows on the dark-field images indicate the direction of nanoparticle movement. In both cases the nanoparticles were moved at an average speed of 5 μm/s. The nanoparticle is seen as a bright green (40 nm) or yellowish (80 nm) spot at the end of the channels. (c) Channels produced with nanoparticles of different sizes have different widths: A nanoparticle 40 nm large leads to a channel 49 nm wide (FWHM); (b) An 80 nm nanoparticle produces channels 98 nm wide (FWHM). The channels are all longer than 10 μm. The PVA layer thickness is ~ 35 nm and ~ 70 nm in the experiments with 40 nm and 80 nm diameter nanoparticles, respectively.

Article Snippet: To demonstrate this method, we use spherical citrate-stabilized gold nanoparticles with diameters of 80 nm and 40 nm purchased from BBInternational.

Techniques: Microscopy, Produced

Journal: ACS nano

Article Title: Sub-Diffraction-Limited Milling by an Optically Driven Single Gold Nanoparticle

doi: 10.1021/nn2023045

Figure Lengend Snippet: Laser embedding of gold nanoparticles into a polymer layer. (a) AFM images clearly show sinking of an 80 nm gold nanoparticle into the polystyrene layer upon plasmonic heating at lower laser powers and crater formation around the nanoparticle due to the thermal decomposition of the polystyrene at higher laser powers. (b) Rayleigh scattering spectra show an increasing refractive index around the nanoparticle seen as a red-shifting and strengthening of the gold nanoparticle scattering. This shows how the embedding process occurs at moderate laser powers. The crater formation results in a blue-shift of the spectra, which occurs due to a decrease of the refractive index around the nanoparticle. The laser power densities and corresponding scattering maxima are shown in panel (b).

Article Snippet: To demonstrate this method, we use spherical citrate-stabilized gold nanoparticles with diameters of 80 nm and 40 nm purchased from BBInternational.

Techniques:

Journal: ACS nano

Article Title: Sub-Diffraction-Limited Milling by an Optically Driven Single Gold Nanoparticle

doi: 10.1021/nn2023045

Figure Lengend Snippet: The lateral optical force depends strongly on the medium refractive index. (a) The axial (along beam axis, Fz) and the radial (along beam radius, Fr) optical forces have been calculated for different media refractive indices. An 80 nm gold nanoparticle has been placed 400 nm below the focal plane in the laser beam (532 nm) propagation direction and 400 nm away from the beam axis. A positive radial force points toward the beam axis, negative – outward. The map of the total optical force exerted in the proximity of the beam waist on an 80 nm gold nanoparticle in (b) air (n=1) and (c) in a polymer-like medium (n=1.52). The forces are calculated in units of pN per 1 mW of total beam power focused to a spot by an objective lens with NA=0.9. For reference, the refractive indices of the glass, PVA and polystyrene are 1.46, 1.52 and 1.55, respectively.

Article Snippet: To demonstrate this method, we use spherical citrate-stabilized gold nanoparticles with diameters of 80 nm and 40 nm purchased from BBInternational.

Techniques: