Nonlinear Optical Properties of Polyaniline

1987 ◽  
Vol 109 ◽  
Author(s):  
A. J. Epstein ◽  
J. M. Ginder ◽  
M. G. Roe ◽  
T. L. Gustafson ◽  
M. Angelopoulos ◽  
...  
Keyword(s):  
Optical Properties ◽  
Laser Intensity ◽  
Emeraldine Base ◽  
Photoinduced Absorption ◽  
Salt Form ◽  
Time Resolved ◽  
Base Form ◽  
Exciton Decay ◽  
Base Polymer ◽  
Molecular Excitons

ABSTRACTPolyaniline is a family of polymers whose electronic and optical properties can be controlled through variation of the number of electrons and protons on the polymer chain. For example, the emeraldine base form of the polymer (EB) is insulating while the emeraldine salt form (ES) is metallic. We present here results for photoinduced absorption spectroscopy of the emeraldine base form of polyaniline. Unlike earlier studied polymers, the spectrum of emeraldine base contains both subgap photoinduced bleaching (at 1.8 eV) and photoinduced absorption (at 0.9, 1.4, and 3.0 eV). The existence of the bleaching peak is consistent with a model of optically excited localized molecular excitons in the emeraldine base polymer. The energies of the three photoinduced absorptions peaks and an associated interband bleaching (at energies greater than ∼3.5 eV) are in agreement with the photogeneration of polaron pairs. Laser intensity studies support that the excitons decay monomolecularly while the polarons decay bimolecularly. Picosecond time-resolved spectroscopy of the exciton decay demonstrates the rapid response of this system.

Anisotropic optical properties of an oriented-emeraldine-base polymer and an emeraldine-hydrochloride-salt polymer

1994 ◽  
Vol 50 (8) ◽  
pp. 5094-5100 ◽  
Author(s):  
R. P. McCall ◽  
E. M. Scherr ◽  
A. G. MacDiarmid ◽  
A. J. Epstein
Keyword(s):  
Optical Properties ◽  
Emeraldine Base ◽  
Hydrochloride Salt ◽  
Base Polymer

Optical Properties and Dynamics of Molecular Excitons in Oligothiophenes

1995 ◽  
Vol 413 ◽  
Author(s):  
R. Tubino ◽  
G. Bongiovanni ◽  
A. Mura ◽  
R. Bosisio ◽  
C. Botfa ◽  
...  
Keyword(s):  
Experimental Data ◽  
Optical Properties ◽  
Solid State ◽  
Inclusion Compound ◽  
Electronic States ◽  
Emission Spectra ◽  
Excited Electronic States ◽  
Exciton Model ◽  
Time Resolved ◽  
Molecular Excitons

ABSTRACTCW absorption and emission spectra as well as time-resolved photoemission dynamics have been employed to detect the evolution of the first excited electronic states and the associated spectroscopical changes in passing from the isolated molecules to the aggregated state in thiophene oligomers. To this end a novel form of inclusion compound in PHTP in which the molecules are electronically decoupled in the solid state has been studied, thus avoiding the complications associated with the change in conformation occurring upon dissolution. The experimental data are interpreted in terms of the molecular exciton model.

Poly(2-methoxyaniline-5-sulfonic Acid) - Surfactant Complexes and Their Redox and Solvatochromic Behaviour

2007 ◽  
Vol 60 (3) ◽  
pp. 159 ◽  
Author(s):  
Simon E. Moulton ◽  
Yingpit Pornputtkul ◽  
Leon A. P. Kane-Maguire ◽  
Gordon G. Wallace
Keyword(s):  
Indium Tin Oxide ◽  
Sulfonic Acid ◽  
Polymer Chains ◽  
Oxidation States ◽  
Emeraldine Base ◽  
Applied Potential ◽  
Emeraldine Salt ◽  
Salt Form ◽  
Base Form ◽  
Redox Switching

Novel stoichiometric (1:1) complexes between the anionic conducting polymer poly(2-methoxyaniline-5-sulfonic acid) (PMAS) and a range of cationic ammonium surfactants have been prepared and characterized. The supramolecular PMAS–surfactant complexes are stable in chloroform and ethanol solutions, in which the PMAS moiety adopts an ‘extended coil’ conformation. Thin films of the complexes can be cast onto indium tin oxide-coated glass from these solutions. The application of an appropriate applied potential leads to redox switching of the PMAS from the emeraldine salt form to its pernigraniline and leucoemeraldine oxidation states. Immersion of the PMAS–surfactant films in 1.0 M NaOH causes the PMAS moiety to undergo conversion into a ‘compact coil’ conformation rather than alkaline de-doping to the emeraldine base form. When the PMAS–surfactant complexes are dissolved in polar organic solvents such as N,N-dimethylformamide, N-methylpyrrolidinone, and acetone, they undergo marked solvatochromism, which is interpreted in terms of rearrangement of the PMAS polymer chains from an ‘extended coil’ to a ‘compact coil’ conformation.

scholarly journals Sulfophosphate Glass Doped with Er3+ and TiO2 Nanoparticles: Thermo-Optical Characterization by Photothermal Spectroscopy

Photonics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 115
Author(s):  
Zeinab Ebrahimpour ◽  
Humberto Cabrera ◽  
Fahimeh Ahmadi ◽  
Asghar Asgari ◽  
Joseph Niemela
Keyword(s):  
Optical Properties ◽  
Tio2 Nanoparticles ◽  
Refractive Index Change ◽  
Optical Path Length ◽  
Beam Deflection ◽  
Time Resolved ◽  
Tio2 Nps ◽  
Amorphous Glass ◽  
Laser Media ◽  
Materials Used

In this work, time-resolved thermal lens and beam deflection methods were applied to determine the thermo-optical properties of Er3+ doped sulfophosphate glass in which different concentrations of Titanium dioxide (TiO2) nanoparticles (NPs) were embedded. Thermal diffusivity (D), thermal conductivity (κ), and the temperature coefficient of the optical path length (ds/dT) were determined as a function of NPs concentrations. Moreover, the growth of TiO2 NPs inside the amorphous glass matrix was evidenced by Transmission Electron Microscopy (TEM) images as well as through optical effects such as refractive index change of the glass. The outcomes indicated relatively high values for D and κ as well as a low ds/dT as required for most optical components used for laser media. The addition of TiO2 NPs with concentration of dopants up to 0.6 mol% improved the optical properties of the glass samples but did not affect its thermal properties. The results indicate that the enhanced optical and thermal performance of the proposed co-doped glass fits the quality standards for materials used in photonic devices.

Coating of Polyaniline with an Insulating Polymer to Improve the Power Efficiency of Electrorheological Fluids

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1931-1939 ◽  
Author(s):  
J. Akhavan ◽  
K. Slack ◽  
V. Wise ◽  
H. Block
Keyword(s):  
Power Efficiency ◽  
Electrorheological Fluids ◽  
Emeraldine Base ◽  
Heavy Duty ◽  
Base Form ◽  
Static Yield ◽  
High Fields ◽  
Er Fluids ◽  
Er Fluid ◽  
A Current

Currents drawn under high fields often present practical limitations to electrorheological (ER) fluids usefulness. For heavy-duty applications where large torques have to be transmitted, the power consumption of a ER fluid can be considerable, and for such uses a current density of ~100μ A cm -2 is often taken as a practical upper limit. This investigation was conducted into designing a fluid which has little extraneous conductance and therefore would demand less current. Selected semi-conducting polymers provide effective substrates for ER fluids. Such polymers are soft insoluble powdery materials with densities similar to dispersing agents used in ER formulations. Polyaniline is a semi-conducting polymer and can be used as an effective ER substrate in its emeraldine base form. In order to provide an effective ER fluid which requires less current polyaniline was coated with an insulating polymer. The conditions for coating was established for lauryl and methyl methacrylate. Results from static yield measurements indicate that ER fluids containing coated polyaniline required less current than uncoated polyaniline i.e. 0.5μ A cm -2. The generic type of coating was also found to be important.

scholarly journals Impact of the ZnO buffer on the optical properties of GaN: time resolved micro-photoluminescence

1999 ◽  
Vol 59 (1-3) ◽  
pp. 163-167 ◽  
Author(s):  
A. Hoffmann ◽  
J. Holst ◽  
A. Kaschner ◽  
H. Siegle ◽  
J. Christen ◽  
...  
Keyword(s):  
Optical Properties ◽  
Time Resolved

scholarly journals Time-Resolved Reflectance Spectroscopy Applied to the Nondestructive Monitoring of the Internal Optical Properties in Apples

2001 ◽  
Vol 55 (10) ◽  
pp. 1368-1374 ◽  
Author(s):  
Rinaldo Cubeddu ◽  
Cosimo D'Andrea ◽  
Antonio Pifferi ◽  
Paola Taroni ◽  
Alessandro Torricelli ◽  
...  
Keyword(s):  
Optical Properties ◽  
Industrial Applications ◽  
Nondestructive Monitoring ◽  
Nondestructive Measurement ◽  
Time Resolved ◽  
Mean Values ◽  
Scattering Coefficients ◽  
Scattering Spectra ◽  
The Mean ◽  
Temporal Dispersion

Time-resolved reflectance has been used for the nondestructive measurement of optical properties in apples. The technique is based on the detection of the temporal dispersion of a short laser pulse injected into the probed medium. The time distribution of re-emitted photons interpreted with a solution of the diffusion equation yields the mean values of the absorption and reduced scattering coefficients of the medium. The proposed technique proved useful for the measurement of the absorption and scattering spectra of different varieties of apples, revealing the spectral shape of chlorophyll. No major variations were observed in the experimental data when the fruit was peeled, showing that the optical properties measured were those of the pulp. With this technique the change in chlorophyll absorption during storage and ripening could be followed. Finally, a compact prototype working at few selected wavelengths was designed and constructed, demonstrating potentialities of the technique for industrial applications.

Luminescence Properties of InGaN/GaN Green Light-Emitting Diodes with Si-Doped Graded Short-Period Superlattice

2021 ◽  
Vol 21 (11) ◽  
pp. 5648-5652
Author(s):  
ll-Wook Cho ◽  
Bom Lee ◽  
Kwanjae Lee ◽  
Jin Soo Kim ◽  
Mee-Yi Ryu
Keyword(s):  
Optical Properties ◽  
Decay Time ◽  
Stark Effect ◽  
Light Emitting Diodes ◽  
Green Light ◽  
Time Resolved ◽  
Light Emitting ◽  
Quantum Confined Stark Effect ◽  
Short Period ◽  
Si Doped

The optical properties of InGaN/GaN green light-emitting diodes (LEDs) with an undoped graded short-period superlattice (GSL) and a Si-doped GSL (SiGSL) were investigated using photoluminescence (PL) and time-resolved PL spectroscopies. For comparison, an InGaN/GaN conventional LED (CLED) without the GSL structure was also grown. The SiGSL sample showed the strongest PL intensity and the largest PL peak energy because of band-filling effect and weakened quantum- confined stark effect (QCSE). PL decay time of SiGSL sample at 10 K was shorter than those of the CLED and GSL samples. This finding was attributed to the oscillator strength enhancement by the reduced QCSE due to the Coulomb screening by Si donors. In addition, the SiGSL sample exhibited the longest decay time at 300 K, which was ascribed to the reduced defect and dislocation density. These results indicate that insertion of the Si-doped GSL structure is an effective strategy for improving the optical properties in InGaN/GaN green LEDs.

Lability of Stationary and Time-Resolved Optical Properties of the Conformationally Locked CFP Chromophore Derivative

2021 ◽  
Vol 47 (3) ◽  
pp. 784-787
Author(s):  
A. M. Bogdanov ◽  
D. A. Gorbachev ◽  
E. R. Zaitseva ◽  
A. Yu. Smirnov ◽  
N. S. Baleeva ◽  
...  
Keyword(s):  
Optical Properties ◽  
Time Resolved ◽  
Conformationally Locked
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