scholarly journals Polystyrene Opals Responsive to Methanol Vapors

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1547 ◽  
Author(s):  
Luca Burratti ◽  
Mauro Casalboni ◽  
Fabio De Matteis ◽  
Roberto Pizzoferrato ◽  
Paolo Prosposito
Keyword(s):  
Photonic Crystals ◽  
Capillary Condensation ◽  
Limit Of Detection ◽  
Incident Angle ◽  
Three Dimensional ◽  
Energy Shift ◽  
Reflectance Spectra ◽  
Vapor Concentration ◽  
Alcohol Vapor ◽  
Vapor Sensing

Photonic crystals (PCs) show reflectance spectra depending on the geometrical structure of the crystal, the refractive index (neff), and the light incident angle, according to the Bragg-Snell law. Three-dimensional photonic crystals (3D-PCs) composed of polymeric sub-micrometer spheres, are arranged in an ordered face cubic centered (fcc) lattice and are good candidates for vapor sensing by exploiting changes of the reflectance spectra. We synthesized high quality polystyrene (PS) 3D-PCs, commonly called opals, with a filling factor f near to the ideal value of 0.74 and tested their optical response in the presence of different concentrations of methanol (MeOH) vapor. When methanol was present in the voids of the photonic crystals, the reflectance spectra experienced energy shifts. The concentration of methyl alcohol vapor can be inferred, due to a linear dependence of the reflectance band maximum wavelength as a function of the vapor concentration. We tested the reversibility of the process and the time stability of the system. A limit of detection (LOD) equal to 5% (v/v0), where v was the volume of methanol and v0 was the total volume of the solution (methanol and water), was estimated. A model related to capillary condensation for intermediate and high methanol concentrations was discussed. Moreover, a swelling process of the PS spheres was invoked to fully understand the unexpected energy shift found for very high methanol content.

Alcohol vapor sensing by cadmium-doped zinc oxide thick films based chemical sensor

2016 ◽  
Vol 30 (12) ◽  
pp. 1650244 ◽  
Author(s):  
R. A. Zargar ◽  
M. Arora ◽  
S. Chackrabarti ◽  
S. Ahmad ◽  
J. Kumar ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Chemical Sensor ◽  
Thick Films ◽  
Film Surface ◽  
Vapor Concentration ◽  
Zinc Oxide Film ◽  
Acetate Dihydrate ◽  
Alcohol Vapor ◽  
Vapor Sensing ◽  
Co Precipitation

Cadmium-doped zinc oxide nanoparticles were derived by simple chemical co-precipitation route using zinc acetate dihydrate and cadmium acetate dihydrate as precursor materials. The thick films were casted from chemical co-precipitation route prepared nanoparticles by economic facile screen printing method. The structural, morphological, optical and electrical properties of the film were characterized relevant to alcohol vapor sensing application by powder XRD, SEM, UV-VIS and DC conductivity techniques. The response and sensitivity of alcohol (ethanol) vapor sensor are obtained from the recovery curves at optimum working temperature range from 20[Formula: see text]C to 50[Formula: see text]C. The result shows that maximum sensitivity of the sensor is observed at 25[Formula: see text]C operating temperature. On varying alcohol vapor concentration, minor variation in resistance has been observed. The sensing mechanism of sensor has been described in terms of physical adsorption and chemical absorption of alcohol vapors on cadmium-doped zinc oxide film surface and inside film lattice network through weak hydrogen bonding, respectively.

Propagation and Reflection of Plane Waves in a Rotating Magneto-Elastic Fibre-Reinforced Semi Space with Surface Stress

2020 ◽  
Vol 22 (4) ◽  
pp. 939-958
Author(s):  
Indrajit Roy ◽  
D. P. Acharya ◽  
Sourav Acharya
Keyword(s):  
Surface Stress ◽  
Incident Angle ◽  
Plane Waves ◽  
Three Dimensional ◽  
Elastic Fibre ◽  
Amplitude Ratios ◽  
Governing Equations ◽  
Rotation Surface ◽  
Wave Velocities ◽  
Magnetic Field Rotation

AbstractThe present paper investigates the propagation of quasi longitudinal (qLD) and quasi transverse (qTD) waves in a magneto elastic fibre-reinforced rotating semi-infinite medium. Reflections of waves from the flat boundary with surface stress have been studied in details. The governing equations have been used to obtain the polynomial characteristic equation from which qLD and qTD wave velocities are found. It is observed that both the wave velocities depend upon the incident angle. After imposing the appropriate boundary conditions including surface stress the resultant amplitude ratios for the total displacements have been obtained. Numerically simulated results have been depicted graphically by displaying two and three dimensional graphs to highlight the influence of magnetic field, rotation, surface stress and fibre-reinforcing nature of the material medium on the propagation and reflection of plane waves.

Other topics

2018 ◽  
Author(s):  
Ted Janssen ◽  
Gervais Chapuis ◽  
Marc de Boissieu
Keyword(s):  
Photonic Crystals ◽  
Crystal Morphology ◽  
Three Dimensional ◽  
Icosahedral Quasicrystal ◽  
Crystal Surfaces ◽  
Decagonal Quasicrystal ◽  
System A ◽  
Fundamental Law ◽  
Quasiperiodic Systems ◽  
Aperiodic Crystals

The law of rational indices to describe crystal faces was one of the most fundamental law of crystallography and is strongly linked to the three-dimensional periodicity of solids. This chapter describes how this fundamental law has to be revised and generalized in order to include the structures of aperiodic crystals. The generalization consists in using for each face a number of integers, with the number corresponding to the rank of the structure, that is, the number of integer indices necessary to characterize each of the diffracted intensities generated by the aperiodic system. A series of examples including incommensurate multiferroics, icosahedral crystals, and decagonal quaiscrystals illustrates this topic. Aperiodicity is also encountered in surfaces where the same generalization can be applied. The chapter discusses aperiodic crystal morphology, including icosahedral quasicrystal morphology, decagonal quasicrystal morphology, and aperiodic crystal surfaces; magnetic quasiperiodic systems; aperiodic photonic crystals; mesoscopic quasicrystals, and the mineral calaverite.

scholarly journals Fabrication of three-dimensional photonic crystals with multilayer photolithography

2005 ◽  
Vol 13 (7) ◽  
pp. 2370 ◽  
Author(s):  
Peng Yao ◽  
Garrett J. Schneider ◽  
Dennis W. Prather ◽  
Eric D. Wetzel ◽  
Daniel J. O'Brien
Keyword(s):  
Photonic Crystals ◽  
Three Dimensional

Optical tuning of three-dimensional photonic crystals fabricated by femtosecond direct writing

2005 ◽  
Vol 87 (9) ◽  
pp. 091117 ◽  
Author(s):  
Dennis McPhail ◽  
Martin Straub ◽  
Min Gu
Keyword(s):  
Photonic Crystals ◽  
Three Dimensional ◽  
Direct Writing

Ingan Quantum Dots Fabricated On Aigan Surfaces -Growth Mechanism And Optical Propertiesh-

1997 ◽  
Vol 482 ◽  
Author(s):  
H. Hirayama ◽  
S. Tanaka ◽  
P. Ramvall ◽  
Y. Aoyagi
Keyword(s):  
Quantum Dots ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Energy Shift ◽  
Organic Chemical ◽  
Self Assembling ◽  
Atomic Force ◽  
Peak Energy ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

AbstractWe demonstrate photoluminescence from self- assembling InGaN quantum dots (QDs), which are artificially fabricated on AlGaN surfaces via metal- organic chemical vapor deposition. InGaN QDs are successfully fabricated by the growth mode transition from step- flow to three dimensional island formation by using anti-surfactant silicon on AlGaN surface. The diameter and height of the fabricated InGaN QDs are estimated to be ˜10nm and ˜5nm, respectively, by an atomic- force- microscope (AFM). Indium mole fraction of InxGal−x N QDs is controlled from x=˜0.22 to ˜0.52 by varying the growth temperature of QDs. Intense photoluminescence is observed even at room temperature from InGaN QDs embedded with the GaN capping layers. In addition, the temperature- dependent energy shift of the photoluminescence peak- energy shows a localization behavior.

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