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    Illustration of the tip-asymmetry effect using Au NPs with 15 nm diameters. The images before (a) and after (b) a manipulation step in which the NP is pushed to the right. The images before (c) and after (d) a manipulation step in which the NP is pushed to the left. (e) A schematic of an asymmetric tip. (f) An SEM image of a typical AFM tip exhibits the asymmetric shape.

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    An AFM image (250 nm x 250 nm) of a typical hexa-QDC.

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    (a) An AFM image of the sample prior to addition of the GaAs capping layer. (b) Spatial image of sample taken using micro-PL setup. (c) Micro-PL data taken from the area shown in (b). (d) Dotted line shows an ensemble measurement. Solid line shows PL intensity from a single row indicated by arrows in (c). Inset: Lorentzian line fit to isolated resonances at higher energy end of the spectrum.

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    (a) Schematic of the energy band profile in a CdSe/ZnS quantum dot with an alloyed core-to-shell transition. (b) 1 x 0.6 lm AFM image of QDs under study. The horizontal line cross-section shows typical sizes of quantum dots. (c) Distribution of QD heights as determined from AFM data. (d) Expanded TEM image of a few quantum dots.

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    (a) Emission trajectory of a single QD with 10 ms binning time. The histogram of count rates shown to the right illustrates the bimodal distribution. On both panels, the solid horizontal line marks on-time cutoff threshold. (b) Weighted distribution of the off-time probability density, with moff 1⁄4 1.6 6 0.1 power-law fit according to Eq. (4b). (c) Decay of the threshold-discriminated on-state with a single-exponential fit.

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    (a) Schematic of experimental setup. (b) AFM topography and (c) simultaneous confocal image of QDs on a glass coverslip. An identical white box in each image helps to illustrate the correspondence between the images. In the AFM image, the four dots located at the corners of the box correspond to the four bright dots in the confocal image. (d) Enlarged AFM image of a QD with a line cut.

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    (a)Ensemble optical spectra: Au NP extinction spectrum (black), QD PL spectrum (red), and excitation laser wavelength (green). (b) AFM image of a QD and Au NPs with a white arrow denoting the path of the Au NP. Emission trajectories and corresponding PL decays are shown for (c, d) the QD alone, (e, f) the QD near the Au NP, and (g, h) the QD after Au NP was pushed away.

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    Experimental set-up for the 2D spectroscopy. The three incident pulses are arranged in a “box” geometry. The four mixing signal copropagating with the reference pulse is characterized via spectral interferometry, where both the electrical field amplitude and phase of the nonlinear signal are determined.

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    (a) Spin wave intensity map recorded for the excitation frequency of 8.9 GHz. (b) Portion of the measured diffraction pattern after the defect. (c) Calculated intensity obtained by taking into account the modes with the order numbers n=1 and 3 only. (d) Calculated pattern for three modes with n=1, 3, and 5.

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    Quadrumer plasmonic ring with Fano resonance in the visible range. (a) Left: a plasmonic quadrumer ring consisting of four gold particles is assembled using an AFM tip. Right: AFM topograph. (b) Left: plasmonic ring quadrumer of four gold nanoparticles. Right: electric dipoles create an overall net zero dipole and no Fano resonance (c) slightly smaller particle breaks the symmetry (left) and creates a net dipole moment (right)

Studies of light-matter interaction in quantum confined system have provided great insight into diverse and fundamental problems such as many-body interactions and quantum entanglement. We use and develop a variety of optical spectroscopy tools. Read more about us.