Polyamic Acid Langmuir-Blodgett (LB) Films Containing A Stable Second-Order NLO Chromophore

1995 ◽  
Vol 413 ◽  
Author(s):  
D. W. Cheong ◽  
J. -I Chen ◽  
J. Kumar ◽  
S. K. Tripathy
Keyword(s):  
Nonlinear Coefficient ◽  
Polarized Light ◽  
Second Order ◽  
Polyimide Films ◽  
Polyamic Acid ◽  
Lb Films ◽  
Langmuir Blodgett ◽  
Number Of Layers ◽  
Absorption Correction ◽  
Nlo Chromophores

ABSTRACTNonlinear optical (NLO) LB films of polyamic acid containing a stable NLO dye were prepared and imidized either chemically or thermally. The optical properties and molecular orientation of these LB films were studied. From the absorption spectra, we infer that the derivative of the pnitroazobenzene chromophore covalently attatched to polyamic acid did not show significant aggregation. Quadratic dependence of SHG on the number of layers in polyamic acid films indicated the noncentrosymmetric organization of polar NLO chromophores. A second-order nonlinear coefficient (d33) of 23.4 pm/V was observed at 1064 nm after absorption correction. In polyimide films, SH intensity was dramatically reduced due to the collapse of the layered structure upon imidization process. In-plane isotropy of the LB films of polyamic acid and polyimide were lost upon irradiation of polarized light.

Generation of Circularly Polarized Light of Highly Oriented Poly(P-Phenylene Vinylene)

2000 ◽  
Vol 660 ◽  
Author(s):  
A. Marletta ◽  
D. Gonçalves ◽  
O. N. Oliveira ◽  
R. M. Faria ◽  
F. E. G. Guimarães
Keyword(s):  
Polarized Light ◽  
Linear Dichroism ◽  
Asymmetry Factor ◽  
Phenylene Vinylene ◽  
Lb Films ◽  
Circularly Polarized Light ◽  
Langmuir Blodgett ◽  
Efficient Energy ◽  
Absorption Experiment ◽  
Linearly Polarized

ABSTRACTLangmuir-Blodgett (LB) films of poly(p-phenylene vinylene) (PPV) were prepared using an amphiphilic precursor, where the counterion chloride was partially replaced by a long chain dodecylbenzenesulfonate ion. These LB-PPV films are highly ordered along the dipping direction as demonstrated by linear dichroism experiments using linearly polarized optical absorption and emission. The intensity ratio between emitted light parallel and perpendicular to the dipping direction was ca. 17, which is much higher than the dichroic ratio of 3.6 found in the polarized absorption experiment. These values indicate an efficient energy and/or charge transfer between low conjugated segments (disordered) and highly conjugated (ordered) ones after excitation. In addition, the LB films displayed large circular polarization with an asymmetry factor ge which varies from 0.6 to –0.2 when the sample temperature is increased from 30 to 300 K.

scholarly journals Evaluation of Damage Process of a Coating by Using Nonlinear Ultrasonic Method

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 440
Author(s):  
Chunguang Xu ◽  
Lei He ◽  
Shiyuan Zhou ◽  
Dingguo Xiao ◽  
Pengzhi Ma
Keyword(s):  
Tensile Stress ◽  
Order Parameter ◽  
Evaluation Method ◽  
Early Stage ◽  
Ultrasonic Method ◽  
Nonlinear Coefficient ◽  
Damage Index ◽  
Second Order ◽  
External Loading ◽  
Nonlinear Ultrasonic

During the service or external loading of the surface coating, the damage accumulation may develop in the coating or at the interface between the substrate and the coating, but it is difficult to measure directly in the early stage, so the acoustic nonlinear parameters are used as the early damage index of the coating. In this paper, the nonlinear wave motion equation is solved by the perturbation method and the new relationship between the relative ratio of second-order parameter and third-order parameter was derived. The nonlinear ultrasonic testing system is used to detect received signals during tensile testing of for the specimen with Al2O3 coatings. It is found that when the stress is less than 260 MPa, the appearance of the coating has no obvious change, but the nonlinear coefficients measured by the experiment increase with the increase of the tensile stress. By comparing the curves of nonlinear coefficients and stress respectively, the fluctuation of curves the second-order nonlinear coefficient A2 and the relative nonlinear coefficient β′ to stress is relatively small, and close to the linear relationship with the tensile stress, which indicates that the two parameters of the specimen with Al2O3 coatings are more sensitive to the bonding conditions, and can be used as an evaluation method to track the coating damage.

Synthesis and properties of a new second-order NLO chromophore containing the benzo[b]furan moiety for electro-optical materials

RSC Advances ◽  
2014 ◽  
Vol 4 (63) ◽  
pp. 33312-33318 ◽  
Author(s):  
Maolin Zhang ◽  
Guowei Deng ◽  
Airui Zhang ◽  
Huajun Xu ◽  
Heyan Huang ◽  
...  
Keyword(s):  
Electron Donor ◽  
Optical Materials ◽  
Furan Ring ◽  
Second Order ◽  
Donor Group ◽  
Nlo Chromophores ◽  
Furan Moiety

We have designed and synthesized a new chromophore having a 1,1,7,7-tetramethyljulolidine fused furan ring as the electron donor group to systematically investigate the role of the benzo[b]furan ring in NLO chromophores.

scholarly journals A Molecular Architectural Approach to Second-Order Nonlinear Optical Materials

1995 ◽  
Vol 392 ◽  
Author(s):  
Xiaoguang Yang ◽  
Duncan McBranch ◽  
Basil Swanson ◽  
Dequan Li
Keyword(s):  
Nonlinear Optical ◽  
Second Harmonic ◽  
Fused Silica ◽  
Second Order ◽  
Nonlinear Susceptibility ◽  
Design And Synthesis ◽  
Fundamental Wavelength ◽  
Assembled Monolayers ◽  
Methylene Groups ◽  
Nlo Chromophores

AbstractThe design and synthesis of a family of calix[4]arene-based nonlinear optical (NLO) chromophores are discussed. The calixarene chromophores are macrocyclic compounds consisting of four simple D-π-A units bridged by methylene groups. These molecules were synthesized such that four D-π-A units of the calix[4]arene were aligned along the same direction with the calixarene in a cone conformation. These nonlinear optical super-chromophores were subsequently fabricated into covalently bound self-assembled monolayers on the surfaces of fused silica and silicon. Spectroscopic second harmonic generation (SHG) measurements were carried out to determine the absolute value of the dominant element of the second-order nonlinear susceptibility, d33, and the average molecular alignment, ψ. We find a value of d33 = 60 pm/V at a fundamental wavelength of 890 nm, and ψ˜ 36° with respect to the surface normal.

Nanoparticle assembly following Langmuir–Hinshelwood kinetics on a Langmuir film and chain networks captured in LB films

2015 ◽  
Vol 17 (11) ◽  
pp. 7386-7394 ◽  
Author(s):  
Lasya Maganti ◽  
Madhuri Jash ◽  
Anju Nair ◽  
T. P. Radhakrishnan
Keyword(s):  
Metal Nanoparticles ◽  
Nanoparticle Assembly ◽  
Deposition Pressure ◽  
Langmuir Film ◽  
Lb Films ◽  
Langmuir Blodgett ◽  
Langmuir Blodgett Films ◽  
Positively Charged

Negatively charged metal nanoparticles assemble as chain networks through Langmuir–Hinshelwood kinetics on a Langmuir film of positively charged amphiphiles. The extension of the networks captured in Langmuir–Blodgett films is tuned by the deposition pressure.

scholarly journals Synthesis and characterization of novel second-order NLO-chromophores bearing pyrrole as an electron donor group

Tetrahedron ◽  
2012 ◽  
Vol 68 (39) ◽  
pp. 8147-8155 ◽  
Author(s):  
M. Cidália R. Castro ◽  
M. Belsley ◽  
A. Maurício C. Fonseca ◽  
M. Manuela M. Raposo
Keyword(s):  
Electron Donor ◽  
Second Order ◽  
Synthesis And Characterization ◽  
Donor Group ◽  
Nlo Chromophores

Photoelectric Cells of Merocyanine Langmuir-Blodgett Films Utilizing Surface Plasmon Excitations

2001 ◽  
Vol 708 ◽  
Author(s):  
Keizo Kato ◽  
Futoshi Takahashi ◽  
Kazunari Shinbo ◽  
Futao Kaneko ◽  
Takashi Wakamatsu
Keyword(s):  
Thin Films ◽  
Surface Plasmon ◽  
Short Circuit ◽  
Schottky Diodes ◽  
Attenuated Total Reflection ◽  
Dielectric Constants ◽  
Type I ◽  
Type Ii ◽  
Lb Films ◽  
Langmuir Blodgett

ABSTRACTShort-circuit photocurrents (ISC) due to surface plasmon (SP) excitations have been investigated for the photoelectric cells using Langmuir-Blodgett (LB) films of merocyanine (MC) dye. The MC dye exhibits p-type conduction, and the Schottky and Ohmic contacts are obtained at the interfaces between MC LB films and Al thin films and between MC LB films and Ag thin films, respectively. Since the Schottky diodes show the photoelectric effects, the Schottky photoelectric cells have been constructed. The cells with two kinds of structures, that is, prism/Al/MC/Ag (type I) and prism/MgF2/Al/MC/Ag (type II), have been prepared. In the attenuated total reflection (ATR) method, the types I and II have the Kretschmann and both the Kretschmann and Otto configurations, respectively. SP has been resonantly excited at the interface between Ag and air for the type I and at the interfaces between MgF2 and Al between Ag and air for the type II. The ATR and the ISC properties have been simultaneously measured as a function of the incident angles of the laser beams. The peaks of the ISC have corresponded to the resonant angles of the ATR curves. The electric fields and optical absorptions in the cells have been also calculated using the dielectric constants and the film thicknesses obtained from the ATR measurements. The calculated absorptions in the MC layers as a function of the incident angles have corresponded to the results of ISC. It has been estimated that the ISC for both types I and II could be enhanced by the excitations of SP in the ATR configurations.

High glass transition temperature syndioregic second-order non-linear optical polymer in Langmuir–Blodgett–Kuhn films

1998 ◽  
Vol 327-329 ◽  
pp. 5-8 ◽  
Author(s):  
M.J. Roberts ◽  
G.A. Lindsay ◽  
J.D. Stenger-Smith ◽  
R.A. Hollins ◽  
A.P. Chafin ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Second Order ◽  
High Glass Transition Temperature ◽  
Langmuir Blodgett ◽  
Optical Polymer ◽  
Non Linear ◽  
Linear Optical
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