244,013 research outputs found
Interferometry of a Single Nanoparticle Using the Gouy Phase of a Focused Laser Beam
We provide a quantitative explanation of the mechanism of the far-field
intensity modulation induced by a nanoparticle in a focused Gaussian laser
beam, as was demonstrated in several recent direct detection studies. Most
approaches take advantage of interference between the incident light and the
scattered light from a nanoparticle to facilitate a linear dependence of the
signal on the nanoparticle volume. The phase relation between the incoming
field and the scattered field by the nanoparticle is elucidated by the concept
of Gouy phase. This phase relation is used to analyze the far-field
signal-to-noise ratio as a function of exact nanoparticle position with respect
to the beam focus. The calculation suggests that a purely dispersive
nanoparticle should be displaced from the Gaussian beam focus to generate a
far-field intensity change
Effect of crosslinker length on the elastic and compression modulus of poly(acrylamide) nanocomposite hydrogels
Polymer hydrogelshave shown to exhibit improved properties upon the addition of nanoparticles; however, the mechanical underpinnings behind these enhancements have not been fully elucidated. Moreover, fewer studies have focused on developing an understanding of how polymer parameters affect the nanoparticle-mediated enhancements. In this study, we investigated the elastic properties of silica nanoparticle-reinforced poly(acrylamide) hydrogels synthesized using crosslinkers of various lengths. Crosslinker length positively affected the mechanical properties of hydrogels that were synthesized with or without nanoparticles. However the degree of nanoparticle enhancement was negatively correlated to crosslinker length. Our findings enable the understanding of the respective roles of nanoparticle and polymer properties on nanoparticle-mediated enhancement of hydrogels and thereby the development of next-generation nanocomposite materials
Nanoparticle Classification in Wide-field Interferometric Microscopy by Supervised Learning from Model
Interference enhanced wide-field nanoparticle imaging is a highly sensitive
technique that has found numerous applications in labeled and label-free
sub-diffraction-limited pathogen detection. It also provides unique
opportunities for nanoparticle classification upon detection. More specif-
ically, the nanoparticle defocus images result in a particle-specific response
that can be of great utility for nanoparticle classification, particularly
based on type and size. In this work, we com- bine a model based supervised
learning algorithm with a wide-field common-path interferometric microscopy
method to achieve accurate nanoparticle classification. We verify our
classification schemes experimentally by using gold and polystyrene
nanospheres.Comment: 5 pages, 2 figure
Highly luminescent perovskite–aluminum oxide composites
In this communication we report on the preparation of CH3NH3PbBr3 perovskite/Al2O3 nanoparticle composites in a thin film configuration and demonstrate their high photoluminescence quantum yield. The composite material is solution-processed at low temperature, using stable alumina nanoparticle dispersions. There is a large influence of the alumina nanoparticle concentration on the perovskite morphology and on its photoluminescence
Digital phase conjugation of second harmonic radiation emitted by nanoparticles in turbid media
We demonstrate focusing coherent light on a nanoparticle through turbid media based on digital optical phase conjugation of second harmonic generation (SHG) field from the nanoparticle. A SHG active nanoparticle inside a turbid medium was excited at the fundamental frequency and emitted SHG field as a point source. The SHG emission was scattered by the turbid medium, and the scattered field was recorded by off-axis digital holography. A phase-conjugated beam was then generated by using a phase-only spatial light modulator and sent back through the turbid medium, which formed a nearly ideal focus on the nanoparticle
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