In: CHIMIA International Journal for Chemistry, 2019, vol. 73, no. 1, p. 47–50
The natural world is teeming with color, which originates either from the wavelength- dependent absorp- tion of light by pigments or from scattering from nanoscale structures, or both. While the latter ' structural color ' has been a topic of intense study in recent years, the most vibrant colors in nature involve contributions from both structure and pigment. The study of structure–pigment...
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In: Nanoscale, 2018, vol. 10, no. 47, p. 22189–22195
The realization of non-close-packed nanoscale patterns with multiple feature sizes and length scales via colloidal self-assembly is a highly challenging task. We demonstrate here the creation of a variety of tunable particle arrays by harnessing the sequential self-assembly and deposition of two differently sized microgel particles at the fluid–fluid interface. The two-step process is...
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In: Applied Physics Letters, 2007, vol. 91, no. 17, p. 171904
Amorphous photonic materials based on dense assemblies of high refractive index spherical particles are presented. Light transmission through these photonic glasses shows a nontrivial wavelength dependence. The transmission spectra can be quantitatively reproduced by modeling the optical properties starting from their building blocks. Our results emphasize the relevance of including short range...
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In: Nature Communications, 2020, vol. 11, no. 1, p. 4867
AbstractLocalization of light is the photon analog of electron localization in disordered lattices, for whose discovery Anderson received the Nobel prize in 1977. The question about its existence in open three-dimensional materials has eluded an experimental and full theoretical verification for decades. Here we study numerically electromagnetic vector wave transmittance through realistic...
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In: Carbohydrate Polymers, 2004, vol. 55, p. 155-161
We have studied the rheological properties of the natural biopolymer system starch in the presence of the gelation inducing flavor compound γ-dodecalactone. From optical microrheology, based on the multiple scattering of laser light (DWS), we deduce the frequency-dependent moduli G(ω) and G″(ω) of the gelling sample over the full frequency range. Our measurements demonstrate the inherent...
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In: Soft Matter, 2010, vol. 6, p. 2174-2177
We describe the synthesis of thermoresponsive, magnetic, optically anisotropic and orientable colloidal particles based on poly(N-isopropylacrylamide) hybrid microgels (PNIPAMs) with an embedded ellipsoidal hematite (α-Fe₂O₃) core. Our ability to orient the particles with a magnetic field is demonstrated by small angle X-ray scattering and by optical polarization microscopy.
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In: European Physical Journal E, 2009, vol. 28, no. 2, p. 165-171
We present a light scattering study of aqueous suspensions of microgel particles consisting of poly(N-Isopropyl-Acrylamide) cross-linked gels. The solvent quality for the particles depends on temperature and thus allows tuning of the particle size. The particle synthesis parameters are chosen such that the resulting high surface charge of the particles prevents aggregation even in the...
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In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2016, vol. 499, p. 18–23
Hierarchical polymer structures such as pNIPAM microgels have been extensively studied for their ability to undergo structural and physical transformations that can be controlled by external stimuli such as temperature, pH or solvent composition. However, a direct three-dimensional visualization of individual particles in-situ has so far been hindered by insufficient resolution, with optical...
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In: Frontiers in Cellular Neuroscience, 2016, p. 142
Understanding synaptic connectivity and plasticity within brain circuits and their relationship to learning and behavior is a fundamental quest in neuroscience. Visualizing the fine details of synapses using optical microscopy remains however a major technical challenge. Super resolution microscopy opens the possibility to reveal molecular features of synapses beyond the diffraction limit....
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In: Physical Review E, 2015, vol. 91, no. 3, p. 032302
We model the packing structure of a marginally jammed bulk ensemble of polydisperse spheres. To this end we expand on the granocentric model [Clusel et al., Nature (London) 460, 611 (2009)], explicitly taking into account rattlers. This leads to a relationship between the characteristic parameters of the packing, such as the mean number of neighbors and the fraction of rattlers, and the radial...
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