Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 38
Book Description
The behaviour of surface and trapped charges that originate during contact electric-field poling of a model guest-host nonlinearly active polymer has been investigated. Charge effects in this films of para-nitroaniline doped polymethylmethacrylate were studied during and after the poling process by simultaneous measurement of the current through the poling circuit and the SHG signal from the polymer system. The poling current present in a fresh sample is found to differ in both magnitude and temporal dependence to that observed in the sample during subsequent polings. These effects are interpreted by the initial presence of ionic impurities in the sample and the injection of charge into the polymer matrix during poling. The magnitude of the steady-state current eventually reached during the poling process is found to depend on temperature and is related to the mobility of charges. A sharp drop-off in SHG signal intensity that occurs when the poling electrodes are grounded is shown to result from the removal of surface charge that orients chromophore dipoles near the surface of the film; the decay in the macroscopic polarization that then occurs is prolonged by charges trapped in the polymer matrix. The build-up of trapped charge explains a memory effect in which the SHG signal relaxation time gradually increases as the polymer is subjected to multiple polings until a steady-state value is reached. Finally, it is demonstrated that the charges trapped in the polymer matrix are released only after the polymer is heated to high above it temperature of glass transition and the SHG signal has completely decayed away. (MM).
Poling Dynamics and Investigation Into the Behavior of Trapped Charges in Poled Polymer Films for Nonlinear Optical Applications
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 38
Book Description
The behaviour of surface and trapped charges that originate during contact electric-field poling of a model guest-host nonlinearly active polymer has been investigated. Charge effects in this films of para-nitroaniline doped polymethylmethacrylate were studied during and after the poling process by simultaneous measurement of the current through the poling circuit and the SHG signal from the polymer system. The poling current present in a fresh sample is found to differ in both magnitude and temporal dependence to that observed in the sample during subsequent polings. These effects are interpreted by the initial presence of ionic impurities in the sample and the injection of charge into the polymer matrix during poling. The magnitude of the steady-state current eventually reached during the poling process is found to depend on temperature and is related to the mobility of charges. A sharp drop-off in SHG signal intensity that occurs when the poling electrodes are grounded is shown to result from the removal of surface charge that orients chromophore dipoles near the surface of the film; the decay in the macroscopic polarization that then occurs is prolonged by charges trapped in the polymer matrix. The build-up of trapped charge explains a memory effect in which the SHG signal relaxation time gradually increases as the polymer is subjected to multiple polings until a steady-state value is reached. Finally, it is demonstrated that the charges trapped in the polymer matrix are released only after the polymer is heated to high above it temperature of glass transition and the SHG signal has completely decayed away. (MM).
Publisher:
ISBN:
Category :
Languages : en
Pages : 38
Book Description
The behaviour of surface and trapped charges that originate during contact electric-field poling of a model guest-host nonlinearly active polymer has been investigated. Charge effects in this films of para-nitroaniline doped polymethylmethacrylate were studied during and after the poling process by simultaneous measurement of the current through the poling circuit and the SHG signal from the polymer system. The poling current present in a fresh sample is found to differ in both magnitude and temporal dependence to that observed in the sample during subsequent polings. These effects are interpreted by the initial presence of ionic impurities in the sample and the injection of charge into the polymer matrix during poling. The magnitude of the steady-state current eventually reached during the poling process is found to depend on temperature and is related to the mobility of charges. A sharp drop-off in SHG signal intensity that occurs when the poling electrodes are grounded is shown to result from the removal of surface charge that orients chromophore dipoles near the surface of the film; the decay in the macroscopic polarization that then occurs is prolonged by charges trapped in the polymer matrix. The build-up of trapped charge explains a memory effect in which the SHG signal relaxation time gradually increases as the polymer is subjected to multiple polings until a steady-state value is reached. Finally, it is demonstrated that the charges trapped in the polymer matrix are released only after the polymer is heated to high above it temperature of glass transition and the SHG signal has completely decayed away. (MM).
Beaux meubles anciens et de style ...
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 1
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 1
Book Description
SPE/ANTEC 1996 Proceedings (Print version/ 3 volumes)
Author: Spe
Publisher: CRC Press
ISBN: 9781566764438
Category : Technology & Engineering
Languages : en
Pages : 1400
Book Description
Publisher: CRC Press
ISBN: 9781566764438
Category : Technology & Engineering
Languages : en
Pages : 1400
Book Description
On the Spectra of Doubly and Trebly Ionized Titanium
Author: Henry Norris Russell
Publisher:
ISBN:
Category : Spectrum analysis
Languages : en
Pages : 30
Book Description
Publisher:
ISBN:
Category : Spectrum analysis
Languages : en
Pages : 30
Book Description
Government Reports Announcements & Index
Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 694
Book Description
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 694
Book Description
Nonlinear Optical and Charge Distribution Studies Probing Electric Field Effects in Polymer Thin Films for Second Order Nonlinear Optical Applications
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 35
Book Description
The goals of the research are two fold; First, determine the internal electric field effects from studies of charge magnitude, symmetry and distribution in dye-doped polymer systems. Second, a better understanding of the electric field effects on the chromophore mobility during and after poling. To this end, several techniques are being employed. Electrochromism technique is being used to determine the charge magnitude inside film samples. The films are 4-dimethylamino-4'-nitrostilbene and disperse red 1 chromophores doped into poly(Methyl methacrylate) guest-host systems. Charge symmetry is also being studies using thermal pulse experiments. Preliminary result show that the charges are distributed linearly in the sample. More tests will be performed in search of any local charge distribution inhomogeneities. An interferometric technique with in-situ poling was used to probe the poling field- induced molecular alignment of the chromophores as a function of temperature. Results are showing the dependence of poling on electric fields (magnitude and polarity). Integrated systems will further reveal the loses in the films due to the field Dependent chromophore orientation.
Publisher:
ISBN:
Category :
Languages : en
Pages : 35
Book Description
The goals of the research are two fold; First, determine the internal electric field effects from studies of charge magnitude, symmetry and distribution in dye-doped polymer systems. Second, a better understanding of the electric field effects on the chromophore mobility during and after poling. To this end, several techniques are being employed. Electrochromism technique is being used to determine the charge magnitude inside film samples. The films are 4-dimethylamino-4'-nitrostilbene and disperse red 1 chromophores doped into poly(Methyl methacrylate) guest-host systems. Charge symmetry is also being studies using thermal pulse experiments. Preliminary result show that the charges are distributed linearly in the sample. More tests will be performed in search of any local charge distribution inhomogeneities. An interferometric technique with in-situ poling was used to probe the poling field- induced molecular alignment of the chromophores as a function of temperature. Results are showing the dependence of poling on electric fields (magnitude and polarity). Integrated systems will further reveal the loses in the films due to the field Dependent chromophore orientation.
Cinderella Writer
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 26
Book Description
Hawaiʻi - Authors - Books - Deborah Iida.
Publisher:
ISBN:
Category :
Languages : en
Pages : 26
Book Description
Hawaiʻi - Authors - Books - Deborah Iida.
Physics Briefs
Author:
Publisher:
ISBN:
Category : Physics
Languages : en
Pages : 1224
Book Description
Publisher:
ISBN:
Category : Physics
Languages : en
Pages : 1224
Book Description
JJAP
Author:
Publisher:
ISBN:
Category : Engineering
Languages : en
Pages : 1042
Book Description
Publisher:
ISBN:
Category : Engineering
Languages : en
Pages : 1042
Book Description
Dynamic Mechanical Behavior of Photocrosslinkable Nonlinear Optical Polymers
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
Book Description
An easily processable photocrosslinking guest-host system with stable second order nonlinear optical properties using polyvinylcinnamate as a host polymer has been developed. Samples were made as free standing films from photo-crosslinkable polyvinylcinnamate and different concentration levels of 3-cinnamoyloxy-4-4-(N, N'-diethylamino)-2-cinnamoyloxy phenyl azo nitrobenzene. Photo-crosslinking was carried out by ultraviolet radiation at the major wavelengths viz. 297 and 313 nm subsequent to corona poling. Dynamic mechanical properties of these polymer films were investigated. The changes in the storage and loss moduli, as well as relaxation behavior of the system upon crosslinking and poling are discussed.
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
Book Description
An easily processable photocrosslinking guest-host system with stable second order nonlinear optical properties using polyvinylcinnamate as a host polymer has been developed. Samples were made as free standing films from photo-crosslinkable polyvinylcinnamate and different concentration levels of 3-cinnamoyloxy-4-4-(N, N'-diethylamino)-2-cinnamoyloxy phenyl azo nitrobenzene. Photo-crosslinking was carried out by ultraviolet radiation at the major wavelengths viz. 297 and 313 nm subsequent to corona poling. Dynamic mechanical properties of these polymer films were investigated. The changes in the storage and loss moduli, as well as relaxation behavior of the system upon crosslinking and poling are discussed.