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Langmuir-Blodgett Films
Published in Arthur T. Hubbard, The Handbook of Surface Imaging and Visualization, 2022
Diacetylenic amphiphiles have been studied in great detail because of the potential application of poly(diacetylene) films in nonlinear optical waveguide devices.49–53 The early systematic studies on diacetylenic amphiphiles were done by Tieke et al.,54 Tieke and Wegner,55 Day and Ringsdorf,56,57 and Day et al.58 It was shown very early that these ultrathin polyacetylenic films of CH3(CH2)m —C=C— C=C—(CH2)8 —COOH, where m ≥ 8, are very stable and have interesting physical properties, for example, photoconductivity.59 Diacetylene polymerization requires specific arrangement of the triple bonds, because the reaction proceeds by means of a 1, 4-addition to the conjugate triple bond.60,61 In general, diacetylenic amphiphiles form rigid films and aggregate even at zero surface pressure. Thus, they form domains at the air-water interface that make them rather useless in integrated optics application. Interestingly enough, it has been observed that a horizontal electric field of 104 V/m above the water surface can increase the domain size from 1–300 μm to 1 mm.62
Tables and Guidelines for Laboratory Safety
Published in Thomas J. Bruno, Paris D.N. Svoronos, CRC Handbook of Basic Tables for Chemical Analysis, 2020
Thomas J. Bruno, Paris D.N. Svoronos
Group 2 Test every 6 months AcetalCumeneCyclohexeneDiacetyleneDicyclopentadieneDiethyl etherDimethyl ether1,4-DioxaneEthylene glycol dimethyl ether (glyme)Methyl acetyleneMethyl isobutyl ketoneMethyl cyclopentaneTetrahydrofuranTetrahydronaphthalene (tetralin)Vinyl ethers
Organic Materials for Third-Order Nonlinear Optics
Published in Hari Singh Nalwa, Seizo Miyata, Nonlinear Optics of Organic Molecules and Polymers, 2020
Perry et al.173 and Yuan et al.176 reported THG ?3values for symmetric end-capped diacetylene and acetylene compounds. Table 17 lists the ?(3)values for symmetric end-capped diacetylene compounds measured by the THG technique. The ?(3)and hyperpolarizability values are larger for diacetylenes with longer ??-conjugations. The bisferrocenyl compound shows the largest optical nonlinearity. Fleitz et al.177 reported nonlinear absorption in diphenyl butadiene, diphenyl butadiyne, and a series of acetylene compounds using the Z-scan technique at 532 nm. The measured nonlinear absorption ? coefficients were 0.8 X IO"", 4.8 X 10"", 2.7 X 10"11, 21 X IO'H. 20 X 10 and 27 X 10 11 cm/W at an intensity of 2.8 X 10'" W/cm2 for diphenyl acetylene, diphenyl butadiene, diphenyl butadiyne, 1,4- bis(phenylethynyl) benzene, bis(4-biphenyl) acetylene, and 4,4'-bis(phenylethynyl)biphenyl, respectively. Very large two-photon absorption cross-sections in bis(4-biphenyl) acetylene and 4,4'-bis(pheny- lethynyl) biphenyl evidenced two-photon allowed states close to 37,590 cm in these compounds.
Probing PAH Formation from Heptane Pyrolysis in a Single-Pulse Shock Tube
Published in Combustion Science and Technology, 2023
Alaa Hamadi, Leticia Piton Carneiro, Fabian-Esneider Cano Ardila, Said Abid, Nabiha Chaumeix, Andrea Comandini
The quantification of the measured species is based on the calibrations of the FID responses performed before the experiments. Standard gas mixtures are used for the calibration of the light species representing the C1-C5 hydrocarbons except for diacetylene (C4H2) and triacetylene (C6H2), whose calibration factors are obtained from high-temperature acetylene (C2H2) pyrolysis experiments through carbon atom conservation. Similarly, liquid fuels are used to calibrate benzene, heptane, toluene, styrene, and phenylacetylene. For all of the above calibrations, mixtures are prepared in stainless steel vessel using the partial pressure method. For small PAHs up to three rings, the calibration procedure differs. Here, the calibrations use gas-phase mixtures prepared in a heated glass vessel (200°C) (Sun et al. 2021b) to minimize surface adsorption (Comandini, Malewicki, and Brezinsky 2012). Uncertainties in species mole fractions are 5% for directly calibrated small species and 10% to 15% for PAH species calibrated in the gas phase. These uncertainties derive from the reproducibility of the single measure when repeated several times and the uncertainties in the composition of the initial reference calibration mixtures which reflect in the accuracy of the calibration curves.
Theoretical and experimental approach of fuel gas and carbon black production from coal tar pitch by thermal plasma process
Published in Environmental Technology, 2023
E. S. P. Prado, F. S. Miranda, A. R. Marquesi, A. Essiptchouk, G. A. Labat Amaral, A. S. da Silva Sobrinho, G. Petraconi, M. R. Baldan
With the increase of temperature >1000 K, the concentration of CH4, H2O and CO2 in pyrolysis decreases gradually and after 1600 K none of these compounds are found in concentration above 0.1 vol.%. Only nitrogen N2 and hydrogen sulfide H2S continue being present in the pyrolysis process at temperature range 1600 — 2000 K. Above 2000 K, these compounds give rise to the formation of CS, HCN and C3N compounds (see Figure 6). The atomic hydrogen rises to 10 vol.% at 3000 K, the acetylene C2H2, and cyanoethynylradical C3N (4 vol.% and 3 vol.% at 3000 K, respectively) and the diacetylene C4H2 (0.7 vol.%). Hydrocyanic acid HCN and carbon monosulfide CS reaches its maximal values of 0.5 vol.% (2500 K) and 0.4 vol.% (2800 K), respectively. The other compounds have concentrations <0.1 vol.%.
Introduction of 5,6-dihydro-4H-cyclopenta[b]thiophene core unit into phenyl-tolane: Expanding the mesophase range and increasing the birefringence and dielectric anisotropy of liquid crystal
Published in Liquid Crystals, 2021
Danyang Wan, Fengjiao Shi, Zhaoyi Che, Lingchao Mo, Minggang Hu, Qiang Guo, Juanli Li, Zhongwei An, Jian Li
It is well known that the birefringence value can be improved by increasing the conjugation length along the long molecular axis and the ethynyl bridge seems to be the most commonly used functional group to achieve this goal. A large number of acetylene unit contained LCs such as tolane [26–31], bistolane [32–35], diphenyl-diacetylene [36–38], phenyltolane [39–41] have been prepared so far. Among these structures, phenyltolane-based liquid crystals were most widely explored since the combination of a three-phenyl ring system with a triple bond can promote the polarisability along the long molecular axis thus to increase the birefringence and afford LCs with a wide mesophase temperature range and high melting point [42]. Hence, we mainly focused on this type of liquid crystals in recent years and some typically molecules had been synthesised to investigate the effect of locations of the triple bond [43], terminal fluorinated group [44,45] and lateral fluorination [46] on the properties of LCs. Despite some good performance phenyl-tolane LCs which presented high birefringences, wide nematic temperature ranges and large dielectric anisotropies were obtained; the effect of the core unit especially different π-conjugated heterocyclic core units which may increase the birefringence value on the properties of molecules still needed to be explored.