Search results for " Optics"

Second-order NLO main-chain polymers by polymerization of poled monomers

1993

A new method of preparing oriented NLO main chain polymers is presented. We synthesized NLO-monomers that consist of donor acceptor substituted tolane molecules that can be poled in the low molar mass state. In the oriented polar state these monomers can be chemically linked using a thermally activated polyaddition reaction. This reaction links the donor head of one monomer to the acceptor tail of the next hibiting bulk noncentrosymmetry with the average direction of the molecular dipoles parallel to the aligning field.

Photoactive Hybrid Materials based on Conjugated Porous Polymers and Inorganic Nanoparticles

2021

This review explores the current state‐of‐the‐art for functional photoactive hybrids containing inorganic nanoparticles (magnetic and metal) and conjugated organic porous polymers (CPPs). Albeit new in the field, with the first hybrid material of this kind reported in 2012, those materials have gained increasing interest in applications such as sensing, heterogeneous catalysis, photocatalysis, and lithium‐ion batteries (LIBs). This review describes the two main synthetic strategies for those materials, namely, 1) using the chemical and morphological features (e.g., porosity and complexation sites) of CPPs to in situ form nanoparticles and 2) fabricating the nanoparticle for templating CPPs.…

Densities and viscosities of imidazolium and pyridinium chloroaluminate ionic liquids

2013

Abstract The chloroaluminate ionic liquids are used in various types of reactions. However, due to their particular vulnerability on water, their physical properties have not been previously investigated very extensively. The densities and viscosities of series imidazolium and pyridinium chloroaluminate ionic liquids having alkyl (butyl, hexyl, octyl) or aralkyl (benzyl, ethylphenyl) chain at the cation, various effective molar fraction of AlCl 3 (χ AlCl3  = 0.5, 0.65, 0.7), as well as they mixture and mixture with common organic solvents (hexane, toluene) were measured at the temperature range 293.15–343.15 K (20–70 °C). Densities, and particularly viscosities decrease with the increase of…

Synthesis, molecular structure, spectroscopic properties and stability of (Z)-N-methyl-C-2,4,6-trimethylphenylnitrone.

2015

Abstract New N-methyl-C-2,4,6-trimethylphenylnitrone 1 has been synthesized starting from N-methylhydroxylamine and mesitaldehyde. The product was fully characterized using different spectroscopic techniques; FTIR, NMR, UV–Vis, high resolution mass spectrometry and X-ray diffraction. The relative stability and percent of population of its two possible isomers (E and Z) were calculated using the B3LYP/6-311++G(d,p) method in gas phase and in solution. In agreement with the X-ray results, it was found that Z-isomer is the most stable one in both gas phase and solution. The molecular geometry, vibrational frequencies, gauge-including atomic orbital (GIAO), and chemical shift values were also c…

Intrinsic Viscosities of Polyelectrolytes: Determination and Modeling of the Effects of Extra Salt

2011

Based on early measurements of J. J. Hermans and co-workers (D. T. F. Pals, J. J. Hermans, Recl. Trav. Chim. Pays-Bas 1952, 71, 513-520; D. T. F. Pals, J. J. Hermans, J. Polym. Sci. 1950, 5, 733-734; D. T. F. Pals, J. J. Hermans, J. Polym. Sci. 1948, 3, 897-898), the present contribution demonstrates how primary data should be evaluated in order to obtain reliable intrinsic viscosities. This procedure yields detailed information on the changes of the intrinsic viscosities and of the corresponding viscometric interaction parameters caused by an increasing salinity of water. Both quantities decline from a maximum value in the pure solvent to a minimum value, which is approached in the limit o…

Absorption spectrum of the f(A1g) ← X(Eg), a(F2g) electronic transition of OsF6

1997

Abstract The absorption spectrum of the visible band of OsF 6 has been recorded using a commercial spectrophotometer. The first vibronic assignments for this band have been realized using the analogy with the d ← X transition of IrF 6 . Some vibronic parameter values are derived.

An MEDT study of the mechanism and selectivities of the [3+2] cycloaddition reaction of tomentosin with benzonitrile oxide

2019

<title>Nonlinear optical properties of some indandione-1,3 pyridinium betaine derivatives</title>

1997

In this paper nonlinear optical properties of indandione-1,3 pyridinium betaine (IPB) molecule and its novel amphiphilic derivatives have been studied. Hyper-Rayleigh scattering (HRS) has been used as a direct and accurate tool to determine effective hyperpolarizability (beta) of IPB derivatives dissolved in chloroform. Evaluation of hyperpolarizability gives an averaged values of (beta) from 140 multiplied by 10-30 to 450 multiplied by 10-30 esu. Disordering of molecular orientation for multilayer Langmuir-Blodgett films of compound C17-IPB has been studied by SHG techniques and discussed for different film thickness. It has been observed that orientation degree of the Z-type molecular str…

Low-energy decay pathways of doubly charged silver clusters $Ag_{n}^{2+}$ (n = 9 - 24)

1997

The low-energy dissociation channels of mass selected silver cluster ions Ag n 2+ (n = 9–24) are determined by collision induced dissociation (CID) in a Penning trap. While all clusters of the size n ≥ 17 evaporate neutral monomers, most smaller clusters undergo asymmetric fission of the form Ag n 2+ → Ag −3 + + Ag {3} + . However, Ag 15 2+ and Ag 11 2+ emit monomers which indicates shell or odd-even effects. The observed fragmentation pathways are different from previous reports of measurements with sputtered Ag n 2+ .

ChemInform Abstract: Preparation and Nonlinear Optics of Monodisperse Oligo(1,4-phenyleneethynylene)s.

2010

Oligo(1,4-phenyleneethynylene)s 1a−e, with solubilizing propoxy side chains, were prepared by use of Hagihara−Sonogashira coupling reactions. The synthetic strategy was based on a building block system and on the use of trimethylsilyl and triisopropylsilyl protecting groups that could be cleaved selectively. The extension of the conjugation with an increasing number of repeat units provokes a bathochromic shift of the long wavelength absorption and a superlinear increase of the second hyperpolarizability |γ|. The corresponding third harmonic generation (THG) measurements were performed using polystyrene matrices and variable laser wavelengths. We conclude that the conjugation length is much…