scholarly journals Empirical formulation of broadband complex refractive index spectra of single-chirality carbon nanotube assembly

Nanophotonics ◽  
2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Taishi Nishihara ◽  
Akira Takakura ◽  
Masafumi Shimasaki ◽  
Kazunari Matsuda ◽  
Takeshi Tanaka ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Refractive Index ◽  
Carbon Nanotube ◽  
Complex Refractive Index ◽  
Wavelength Region ◽  
Refractive Indices ◽  
Gel Chromatography ◽  
Optical Resonances ◽  
Visible Wavelength ◽  
Nanotube Membranes

Abstract Assemblies of single-walled carbon nanotubes with a specific chiral structure are promising future optofunctional materials because of their strong light–matter coupling arising from sharp optical resonances of quasi-one-dimensional excitons. Their strong optical resonances, which lie in the infrared-to-visible wavelength region, can be selected by their chiralities, and this selectivity promises a wide range of applications including photonic and thermo-optic devices. However, the broadband complex optical spectra of single-chirality carbon nanotube assemblies are scarce in the literature, which has prevented researchers and engineers from designing devices using them. Here, we experimentally determine broadband complex refractive index spectra of single-chirality carbon nanotube assemblies. Free-standing carbon nanotube membranes and those placed on sapphire substrates were fabricated via filtration of the nanotube solution prepared by the separation method using gel chromatography. Transmission and reflection spectra were measured in the mid-infrared to visible wavelength region, and the complex refractive indices of nanotube assemblies were determined as a function of photon energy. The real and imaginary parts of the refractive indices of the nanotube membrane with a bulk density of 1 g cm−3 at the first subband exciton resonance were determined to be approximately 2.7–3.6 and 1.3i–2.4i, respectively. We propose an empirical formula that phenomenologically describes the complex refractive index spectra of various single-chirality nanotube membranes, which can facilitate the design of photonic devices using carbon nanotubes as the material.

Immobilization of laccase on functionalized multiwalled carbon nanotube membranes and application for dye decolorization

RSC Advances ◽  
2016 ◽  
Vol 6 (115) ◽  
pp. 114690-114697 ◽  
Author(s):  
Abdelmageed M. Othman ◽  
Elena González-Domínguez ◽  
Ángeles Sanromán ◽  
Miguel Correa-Duarte ◽  
Diego Moldes
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Dye Decolorization ◽  
Myceliophthora Thermophila ◽  
Multiwalled Carbon ◽  
Continuous Processes ◽  
Nanotube Membranes ◽  
Carbon Nanotube Membranes ◽  
Functionalized Multiwalled Carbon Nanotubes ◽  
Supporting Membrane

Myceliophthora thermophilalaccase was covalently immobilized on functionalized multiwalled carbon nanotubes (MWNT) arranged over a supporting membrane to obtain a permeable bio-barrier that could be applied in multibatch or continuous processes.

Mechanism of Ion Exclusion by Sub-2nm Carbon Nanotube Membranes

2008 ◽  
Vol 1106 ◽  
Author(s):  
Francesco Fornasiero ◽  
Hyung Gyu Park ◽  
Jason K Holt ◽  
Michael Stadermann ◽  
Costas P Grigoropoulos ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Electrostatic Interactions ◽  
Ion Selectivity ◽  
Molecular Transport ◽  
Water Desalination ◽  
Oxygen Plasma Treatment ◽  
Nanotube Membranes ◽  
Ion Exclusion ◽  
Carbon Nanotube Membranes

AbstractCarbon nanotubes offer an outstanding platform for studying molecular transport at nanoscale, and have become promising materials for nanofluidics and membrane technology due to their unique combination of physical, chemical, mechanical, and electronic properties. In particular, both simulations and experiments have proved that fluid flow through carbon nanotubes of nanometer size diameter is exceptionally fast compared to what continuum hydrodynamic theories would predict when applied on this length scale, and also, compared to conventional membranes with pores of similar size, such as zeolites. For a variety of applications such as separation technology, molecular sensing, drug delivery, and biomimetics, selectivity is required together with fast flow. In particular, for water desalination, coupling the enhancement of the water flux with selective ion transport could drastically reduce the cost of brackish and seawater desalting. In this work, we study the ion selectivity of membranes made of aligned double-walled carbon nanotubes with sub-2 nm diameter. Negatively charged groups are introduced at the opening of the carbon nanotubes by oxygen plasma treatment. Reverse osmosis experiments coupled with capillary electrophoresis analysis of permeate and feed show significant anion and cation rejection. Ion exclusion declines by increasing ionic strength (concentration) of the feed and by lowering solution pH; also, the highest rejection is observed for the salts (A=anion, C=cation, z= valence) with the greatest zA/zC ratio. Our results strongly support a Donnan-type rejection mechanism, dominated by electrostatic interactions between fixed membrane charges and mobile ions, while steric and hydrodynamic effects appear to be less important. Comparison with commercial nanofiltration membranes for water softening reveals that our carbon nanotube membranes provides far superior water fluxes for similar ion rejection capabilities.

scholarly journals Complex refractive indices of Saharan dust samples at visible and near UV wavelengths: a laboratory study

2011 ◽  
Vol 11 (7) ◽  
pp. 21363-21427 ◽  
Author(s):  
R. Wagner ◽  
T. Ajtai ◽  
K. Kandler ◽  
K. Lieke ◽  
C. Linke ◽  
...  
Keyword(s):  
Refractive Index ◽  
Complex Refractive Index ◽  
Mineralogical Composition ◽  
Sensitivity Study ◽  
Saharan Dust ◽  
Dust Particles ◽  
Particle Analysis ◽  
Refractive Indices ◽  
Aerosol Chamber ◽  
Electron Microscopical

Abstract. We have retrieved the wavelength-dependent imaginary parts of the complex refractive index for five different Saharan dust aerosol particles of variable mineralogical composition at wavelengths between 305 and 955 nm. The dust particles were generated by re-dispersing soil samples into a laboratory aerosol chamber, typically yielding particle sizes with mean diameters ranging from 0.3 to 0.4 μm and maximum diameters from 2 to 4 μm. The extinction and absorption coefficients as well as the number size distribution of the dust particles were simultaneously measured by various established techniques. An inversion scheme based on a spheroidal dust model was employed to deduce the refractive indices. The retrieved imaginary parts of the complex refractive index were in the range from 0.003 to 0.005, 0.005 to 0.011, and 0.016 to 0.050 at the wavelengths 955, 505, and 305 nm. The hematite content of the dust particles was determined by electron-microscopical single particle analysis. Hematite volume fractions in the range from 1.1 to 2.7 % were found for the different dusts, a range typical for atmospheric mineral dust. We have performed a sensitivity study to assess how accurately the retrieved imaginary refractive indices could be reproduced by calculations with mixing rule approximations using the experimentally determined hematite contents as input.

scholarly journals Effect of Aging with Pollution on the Complex Refractive Index of Pure Submicron Clay Particles

2021 ◽  
Vol 8 (1) ◽  
pp. 31
Author(s):  
Sarla Yadav ◽  
Sumit Kumar Mishra
Keyword(s):  
Refractive Index ◽  
Complex Refractive Index ◽  
Chemical Properties ◽  
Radiative Properties ◽  
Submicron Particles ◽  
Visible Range ◽  
Refractive Indices ◽  
Clay Particles ◽  
Physico Chemical ◽  
Refractive Index Data

Modelling the optical and radiative properties of atmospheric particles is governed by one of the key input parameters, i.e., the refractive index of aerosols. Availability of the region-specific refractive index data of aerosols is a major challenge for the atmospheric community. The refractive index of aerosols is a function of their physico-chemical properties. Uncertainty in the computation of the spectral refractive indices of aerosols leads to erroneous assessment of their optical and radiative properties. In the present work, the refractive indices of pure clay (kaolinite, illite) and polluted clay with anthropogenic hematite, AH (0.10 to 1.48%) submicron particles have been computed for the wavelength range of 0.38 to 1.2 µm. Anthropogenic hematite enhanced the overall absorption in the UV and visible range with maximum absorption at lower wavelengths (less than 0.55 µm).

Infrared Refractive Index of Thin YBa2Cu307 Superconducting Films

1992 ◽  
Vol 114 (3) ◽  
pp. 644-652 ◽  
Author(s):  
Z. M. Zhang ◽  
B. I. Choi ◽  
T. A. Le ◽  
M. I. Flik ◽  
M. P. Siegal ◽  
...  
Keyword(s):  
Refractive Index ◽  
Complex Refractive Index ◽  
Wavelength Region ◽  
Wave Theory ◽  
Superconducting Films ◽  
High Tc ◽  
Thin Film Optics ◽  
Infrared Spectrometer ◽  
Thickness Independent ◽  
Constant Refractive Index

This work investigates whether thin-film optics with a constant refractive index can be applied to high-Tc superconducting thin films. The reflectance and transmittance of YBa2Cu3O7 films on LaAlO3 substrates are measured using a Fourier-transform infrared spectrometer at wavelengths from 1 to 100 μm at room temperature. The reflectance of these superconducting films at 10 K in the wavelength region from 2.5 to 25 μm is measured using a cryogenic reflectance accessory. The film thickness varies from 10 to 200 nm. By modeling the frequency-dependent complex conductivity in the normal and superconducting states and applying electromagnetic-wave theory, the complex refractive index of YBa2Cu3O7 films is obtained with a fitting technique. It is found that a thickness-independent refractive index can be applied even to a 25 nm film, and average values of the spectral refractive index for film thicknesses between 25 and 200 nm are recommended for engineering applications.

scholarly journals Giant Gate-Tunability of Complex Refractive Index in Semiconducting Carbon Nanotubes

ACS Photonics ◽  
2020 ◽  
Vol 7 (10) ◽  
pp. 2896-2905
Author(s):  
Baokun Song ◽  
Fang Liu ◽  
Haonan Wang ◽  
Jinshui Miao ◽  
Yueli Chen ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Refractive Index ◽  
Complex Refractive Index

scholarly journals Methods comparison to retrieve the refractive index of small scatterers

2015 ◽  
Vol 12 (22) ◽  
pp. 18723-18768 ◽  
Author(s):  
A.-M. Sánchez ◽  
J. Piera
Keyword(s):  
Refractive Index ◽  
Complex Refractive Index ◽  
Refractive Indices ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Simulation Tools ◽  
Inherent Optical Properties ◽  
Angular Scattering ◽  
Different Shapes ◽  
Small Scatterers

Abstract. Simulation tools to generate the inherent optical properties of small scatterers are useful to complement data difficult to measure, as for instance their angular scattering features. However, in most cases, shapes are reduced to homogeneous spheres, which is a gross simplification for any particles in water, and the inner complex refractive index is estimated using some approximations. In this paper, several methods for the retrieval of the refractive indices are used in three different examples modelling different shapes and particle size distributions. The error associated with each method is discussed and analysed. It is finally demonstrated that those inverse methods using a genetic algorithm provide optimal estimations relative to other techniques that, although faster, are less accurate. The obtained results suggest that phytoplankton models can be improved using this kind of algorithms and a suitable shape.

Complex Refractive Index Determination for Uniaxial Anisotropy with the Use of Kramers—Kronig Analysis

1997 ◽  
Vol 51 (9) ◽  
pp. 1287-1293 ◽  
Author(s):  
Kiyoshi Yamamoto ◽  
Hatsuo Ishida
Keyword(s):  
Refractive Index ◽  
Anisotropic Material ◽  
Total Internal Reflection ◽  
Optical Axis ◽  
Complex Refractive Index ◽  
Uniaxial Anisotropy ◽  
Refractive Indices ◽  
Reflection Spectra ◽  
Dispersion Theory ◽  
Single Interface

Kramers—Kronig analysis of reflection spectra from a single interface with perpendicular ( s) and parallel ( p) polarization has been theoretically studied. The reflection spectra have been simulated from the complex refractive indices based on dispersion theory by using Fresnel equations for an anisotropic material whose optical axis is normal to the surface. The errors in anisotropic complex refractive indices obtained from simulated reflection spectra by Kramers—Kronig analysis have been examined for such techniques as external and total internal reflection spectroscopies.

scholarly journals Complex refractive indices of Saharan dust samples at visible and near UV wavelengths: a laboratory study

2012 ◽  
Vol 12 (5) ◽  
pp. 2491-2512 ◽  
Author(s):  
R. Wagner ◽  
T. Ajtai ◽  
K. Kandler ◽  
K. Lieke ◽  
C. Linke ◽  
...  
Keyword(s):  
Refractive Index ◽  
Complex Refractive Index ◽  
Mineralogical Composition ◽  
Sensitivity Study ◽  
Saharan Dust ◽  
Dust Particles ◽  
Particle Analysis ◽  
Refractive Indices ◽  
Aerosol Chamber ◽  
Electron Microscopical

Abstract. We have retrieved the wavelength-dependent imaginary parts of the complex refractive index for five different Saharan dust aerosol particles of variable mineralogical composition at wavelengths between 305 and 955 nm. The dust particles were generated by dispersing soil samples into a laboratory aerosol chamber, typically yielding particle sizes with mean diameters ranging from 0.3 to 0.4 μm and maximum diameters from 2 to 4 μm. The extinction and absorption coefficients as well as the number size distribution of the dust particles were simultaneously measured by various established techniques. An inversion scheme based on a spheroidal dust model was employed to deduce the refractive indices. The retrieved imaginary parts of the complex refractive index were in the range from 0.003 to 0.005, 0.005 to 0.011, and 0.016 to 0.050 at the wavelengths 955, 505, and 305 nm. The hematite content of the dust particles was determined by electron-microscopical single particle analysis. Hematite volume fractions in the range from 1.1 to 2.7% were found for the different dusts, a range typical for atmospheric mineral dust. We have performed a sensitivity study to assess how accurately the retrieved imaginary refractive indices could be reproduced by calculations with mixing rule approximations using the experimentally determined hematite contents as input.

Complex Refractive Index Determination of Bulk Materials from Infrared Reflection Spectra

1995 ◽  
Vol 49 (5) ◽  
pp. 639-644 ◽  
Author(s):  
Kiyoshi Yamamoto ◽  
Akio Masui
Keyword(s):  
Refractive Index ◽  
Prior Information ◽  
Complex Refractive Index ◽  
Refractive Indices ◽  
Angle Of Incidence ◽  
Reflection Spectra ◽  
Bulk Materials ◽  
Infrared Reflection ◽  
Normal Angle

Kramers-Kronig analysis is applied to extract complex refractive indices of an isotropic single crystal, ceramics, glasses, and organic materials from their infrared external reflection spectra measured near the normal angle of incidence. It is demonstrated that this technique is versatile and can obtain complex refractive indices of materials. The great advantage of this technique is that a wide variety of materials (organic to inorganic, solid to liquid) can be analyzed and that no prior information is required for the analysis. The calculation procedure of the principal integration in Kramers–Kronig analysis of reflection spectra is also presented.

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