Properties of nano-scaled disperse media investigated by refractometric measurements

Sarov, Y.; Capek, Ignác; ̆ková, S. Janíc; Kostic̆, I.; Ani, Nikova; Matay, L.; Sarova, V.

doi:10.1016/j.vacuum.2004.07.019

Cited by 4 publications

(6 citation statements)

References 10 publications

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“…1 By varying the composition of the dispersed and continuous phases prior to emulsification and flow conditions during emulsification, it is possible to create many different kinds of nanoemulsions that have controlled droplet radial size distributions, 1,2 structures, [6][7][8] and physical properties, 9,10 making them advantageous for certain products, such as foods and cosmetics. 3,11 Although light scattering from colloidal dispersions has been extensively studied, both experimentally and theoretically, 12,13 simple optical refractometry of colloidal systems in the visible spectrum has attracted much less attention, perhaps because the information content of refractometry is reduced by averaging.…”

Section: Introductionmentioning

confidence: 99%

Optically probing nanoemulsion compositions

Zhu

Fryd

Huang

et al. 2012

Phys. Chem. Chem. Phys.

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Many types of colloids, including nanoemulsions, which contain sub-100 nm droplets, are dispersed in molecular and micellar solutions, especially surfactant solutions that confer stability. Since it would be desirable to measure the droplet volume fraction ϕ and surfactant concentration C of a nanoemulsion non-destructively, and since the droplet and surfactant structures are significantly smaller than the shortest wavelengths of visible light, optical refractometry could provide a simple and potentially useful approach. By diluting a silicone oil-in-water nanoemulsion having an unknown ϕ and C with pure water, measuring its refractive index n(ϕ,C) using an Abbé refractometer, and fitting the result using a prediction for n that treats the nanoemulsion as an effective medium, we show that ϕ and C can be deduced accurately over a relatively wide range of compositions. Moreover, we generalize this approach to other types of nanoemulsions in which a molecular constituent partitions in varying degrees between the dispersed and the continuous phases.

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Section: Introductionmentioning

confidence: 99%

Optically probing nanoemulsion compositions

Zhu

Fryd

Huang

et al. 2012

Phys. Chem. Chem. Phys.

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“…For example, there have been attempts to measure an effective refractive index for the coherent beam in a turbid suspension of large particles, using the same experimental procedure as the one used to measure the refractive index of homogeneous media. [16][17][18][19][20] Nevertheless, the naive use of this effective index of refraction in CE could lead to large errors, for example, if the reflection of the coherent beam is involved. We have recently shown that the measured reflection coefficients of the coherent wave from a turbid suspension with a flat interface are not consistent with the results obtained when its effective refractive index is substituted in Fresnel's relations.…”

Section: Introductionmentioning

confidence: 99%

Nonlocal nature of the electrodynamic response of colloidal systems

2007

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In this paper we describe the propagation of the coherent component of an electromagnetic wave in a colloidal system with large inclusions using an effective-medium approach. We show that the effective medium is nonlocal ͑spatially dispersive͒ and derive expressions for the nonlocal longitudinal and transverse components of the dielectric response, ⑀ L and ⑀ T . Numerical calculations of the wave-vector dependence of these response functions are displayed. The dispersion relation for the transverse modes is calculated and compared with the results obtained using well-known approximations for the effective index of refraction. It is also shown that some of these approximations have actually a nonlocal nature, explaining why it is not possible to use them to calculate, for example, the reflection properties of the colloidal system using conventional continuum electrodynamics. We also calculate the effective nonlocal electric permittivity ⑀ and effective nonlocal magnetic susceptibility and show that this more traditional description is equivalent to the one using ⑀ L and ⑀ T .

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“…3 This makes it an ideal technique for measurements of the ERI of turbid and scattering media because extremely small optical changes, resulting from changes in the concentration, size, or composition of the particles can be detected. [2][3][4][5][6][7][8] Complementary to total internal reflection (TIR) refractometry, different grating couplers on planar optical waveguides or fiber grating sensors use the evanescent field for (bio)chemical fluidic detection. [9][10] In such type of sensors, the diffraction grating (DG) has an indirect sensing function: to define the sensing area, where the waveguided propagation is frustrated and the evanescent field interacts with the liquid.…”

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confidence: 99%

“…The polarization direction is set at the rotator of polarization (2). For several important reasons, the photodetector (9) measures the DE η of the zeroth order of the pattern (8). First, the zeroth diffraction order is of the strongest orders.…”

mentioning

confidence: 99%

“…Critical angle refractometry takes advantage of the high sensitivity of the relative complex refractive index (RI) when optical reflectance occurs at an interface near the critical angle . This makes it an ideal technique for measurements of the ERI of turbid and scattering media because extremely small optical changes, resulting from changes in the concentration, size, or composition of the particles can be detected. −

1 Structure of the microfluidic sensor and optical setup: (1) diode laser, (2) rotator of polarization, (3) PMMA micro-prism, (4) Al diffraction grating, (5) sealing layer, (6) microchannel, (7) in- and outlet nozzles, (8) diffraction pattern, and (9) photodetector. …”

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confidence: 99%

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On Total Internal Reflection Investigation of Nanoparticles by Integrated Micro-Fluidic System

et al. 2007

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We report on a novel sensor for characterization of nanoparticles colloidal suspensions. We employ a diffraction grating under total internal reflection for investigation of nanodisperse fluids passing through an integrated microfluidic channel. Dispersions containing polymeric, metallic, and ferromagnetic nanoparticles are studied. Using this device, we can accurately determine in real-time the specific refractive index for the nanoparticle suspension and the nanoparticle concentration. The nanoparticle concentrations can be calculated with a resolution of 0.3-0.5 wt% for polymeric nanoparticles, 0.03-0.05 wt% for metallic nanoparticles, and 0.05-0.1 wt% for ferromagnetic nanoparticles. This translates to an effective refractive index that can be determined with an accuracy of 7 x 10(-4) for the polymeric and 2 x 10(-4) for the metallic and ferromagnetic dispersions.

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Properties of nano-scaled disperse media investigated by refractometric measurements

Cited by 4 publications

References 10 publications

Optically probing nanoemulsion compositions

Optically probing nanoemulsion compositions

Nonlocal nature of the electrodynamic response of colloidal systems

On Total Internal Reflection Investigation of Nanoparticles by Integrated Micro-Fluidic System

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