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•MMA is an insulator due to its wide band gap of 6.20 eV.•trans-MMA has a dielectric constant close to that of good insulators; while cis-MMA exhibits a dielectric behaviour close to ...that of polymeric substances.•MMA isomers exhibit weak optical properties such as second- and third-order optical susceptibility and cannot suitable for second and third harmonic generation.•Both forms of MMA absorb and emit mainly in the UV and that the Stokes shift of MMA is low, reducing its potential use in devices such as solar cells.•The conformation enhances second-order NLO response by at least 2 times when moving from cis- to trans-MMA, whereas the third-order response is almost unaffected.
Using Density Functional Theory (DFT) and time-dependent DFT (TD-DFT), we studied a compound widely used in daily life, namely: Methyl Methacrylate (MMA) monomer in its two stable isomers, cis-MMA and trans-MMA. The impact of conformation on the optical and electronic properties of MMA was highlighted. Structural parameters and thermodynamic properties were also assessed, and allowed to discuss the stability and reactivity of this compound. In addition, analysis of optoelectronic and electronic properties, global reactivity descriptors, natural bond orbital (NBO), and hole and electron reorganization energies was performed. The absorption and fluorescence properties, as well as the linear and nonlinear optical (NLO) properties of MMA were also investigated. The findings show that MMA is an insulator due to its wide band gap of 6.20 eV. It also exhibits good optoelectronic properties with high average electric field values of about 5.90 × 109 Vm−1 for cis-MMA and 5.42 × 109 Vm−1 for trans-MMA and high electric displacement values of at least 14.65 × 10-2 cm−2 for cis-MMA and 14.33 × 10-2 cm−2 for trans-MMA, suggesting a potential use for the design of piezoelectric and pyroelectric materials. In addition, trans-MMA has a dielectric constant close to that of good insulators; while cis-MMA exhibits a dielectric behaviour close to that of polymeric substances. Further, these materials are thermodynamically stable in its two conformations, with a good reactivity which can lead to good ability of polymerization. The analysis of the UV–vis spectra revealed that both forms of MMA absorb and emit mainly in the UV and that the Stokes shift of MMA is low, reducing its potential use in devices such as solar cells. At NLO level, MMA isomers exhibit weak optical properties such as second- and third-order optical susceptibility and cannot suitable for second and third harmonic generation; however, the conformation enhances second-order NLO response by at least 2 times when moving from cis- to trans-MMA, whereas the third-order response is almost unaffected. In addition, the conformation also affects the electronic and optoelectronic properties of MMA.
Hartree-Fock (HF) and Density Functional Theory (DFT) were used to investigate the structural, optoelectronic, thermodynamic and nonlinear optical properties of two styrylquinoline monomers; the ...virgin styrylquinoline monomer (M1) and the derivative monomer (M2) with the NO2 group. The results show that these two materials have good optoelectronic properties with respect to very high electric fields in particular from 3.50 × 109 Vm-1 up to 5.52 × 109Vm−1. In addition, the substitution of the H atom by the nitro group induces an increase in both ionization potential and electronic affinity, as well as a reduction in the fundamental electronic gap. The energy gap value of 3.82 eV for M1 and of 3.43 eV of M2, allows us to conclude that our molecules are semiconductors and find applications in the design of solar cells. The determination of thermodynamic properties has revealed thermodynamically stable materials with significant reactivity that are suitable for reactions with other compounds. Further, the high values of linear and nonlinear optical properties led us to conclude that these materials have very good linear and nonlinear optical properties and therefore can be used in telecommunication and signal processing.
•The structural parameters and thermodynamic analysis have revealed thermodynamically stable materials.•The energy gap values of 3.82 eV for M1 and of 3.43 eV of M2, show that they are the semiconductor materials.•The two molecular systems exhibit good linear and nonlinear properties.•The reactivity of monomers containing styrylquinoline is improved by the substitution of the H atom by the nitro group.•Higher refractive index than glass can be used under strong electric fields of the order of 3.50 × 109 Vm-1 up to 5.52 × 109Vm−1.
Hartree-Fock (HF) and Density Functional Theory (DFT) studies were conducted to assess the impact of potassium doping on the thermodynamic, optoelectronic, electronic and nonlinear optical properties ...and on the reactivity of photochromic polymers containing styrylquinoline fragments. Doping was carried out on the virgin monomer (M1) and on the derivative monomer (M2) with the nitro group NO2. Three doped monomers were investigated including, the monomer M3 obtained from M1 by substituting the H atom with a potassium, the monomer M4 by substituting two H atoms and the monomer M5 obtained from M2 by substituting the H atom. Findings proved that the use of potassium and the nitro group is an excellent process to improve the electronics properties of styrylquinoline virgin monomers. In fact, the energy gap decreases from 3.82 eV for M1 to 3.02 eV and to 2.92 eV for M3 and M4, respectively; while the decrease from 3.43 eV for M2 to 2.52 eV for M5 was observed, thus demonstrating the good semiconductor character of the obtained compounds with relevant applications in the manufacture of solar cells. Likewise, the fundamental gap decreases from 6.50 eV for M1 to 5.34 eV and to 4.62 eV for M3 and M4, respectively; while the decrease from 6.11 eV for M2 to 5.21 eV for M5 was observed; thus demonstrating an improvement in the reactivity of our doped monomers. In addition, potassium doping is an appropriate method to enhance optoelectronic properties of styrylquinoline virgin monomers. Thus, the refractive index of our doped monomers is greater than that of glass, which is a reference in optic and can be used under high electric fields of the order of 1.90×109 Vm−1 for monomer M4 up to 7.01×109 Vm−1 for M3 and to 10.89×109 Vm−1 for M5. Finally, the strong enhancement of the linear and nonlinear optical (NLO) properties that we observed leads us to conclude that these doped monomers can be appropriate candidates in devices requiring good NLO properties.
Styrylquinoline; Doping; HF/DFT; Nonlinear optical properties; Electronic properties; Energy gap
•Porous geopolymer applying control of the viscosity, expansion and porosity.•The control of the phases percolation with pores evolution.•Qualitative and quantitative description of fine and ...capillary pores.•Description of the effective thermal conductivity in relation with the pore network.
Rice hush (R) and volcanic (P) ashes, two recycled natural wastes were used for their high amorphous silica to improve the homogeneity and structure composition of inorganic polymer pastes before the expansion with aluminum powder. The fine powders were found to be appropriate in enhancing the geopolymerization and expansion conducting to lightweight structure with pore size and pore distribution linked to the viscosity, the concentration of blowing agent, and the crystalline nature of the waste. From the Stereo optical microscope, environmental scanning microscope and the mercury intrusion porosimetry used for the characterization, it appeared that in the interval of complete percolation of the skeleton, there exists correlation between the viscosity, expansion, roundness of pores, pores size distribution. The interpretation of the microstructure of porous geopolymer in this interval allows the description of their effective thermal conductivity with the Maxwell–Eucken model and the novel effective medium theory proposed recently.
Computational studies based on Density Functional Theory (DFT) and time-dependent DFT (TD-DFT) were used to determine molecular and thermodynamic parameters, optoelectronic and electronic properties, ...as well as chemical descriptors, UV–vis spectra and nonlinear optical response of the chromophores of 2-Styrylquinoline (M01) and 2-(3-nitrostyryl)quinoline (M02). We evaluated the impact of the substitution of the hydrogen atom in M01 by the nitro group (NO
2
) to obtain the molecule M02. The results show very good optoelectronic properties with respect to very high electric fields of the order of 1.43 × 10
9
Vm
−1
for M01 up to 5.26 × 10
9
Vm
−1
for M02. The energy gap decreases from 3.94 eV for M01 to 3.56 eV for M02; which suggest that they are semiconductors. In addition, these two molecules exhibit ionization potential (IP) and electron affinity (EA) quite close to those of Alq
3
and could therefore be good candidates for the manufacture of Organic Light-Emitting Diodes (OLED). The chemical descriptors were assessed and allowed us to discuss the stability and reactivity of our molecules. Thus, the addition of the nitro group to the virgin 2-Styrylquinoline decreases the reactivity and stability of the 2-Styrylquinoline. The analysis of the IR and Raman vibrational spectra shows several peaks between 100 cm
−1
and 3200 cm
−1
of which the most intense for the molecule M01 are attributed to the stretching mode of the C–H bond in the phenyl ring and the C=C double bond in the quinoline ring. For the M02 molecule, stronger peaks were assigned to the stretching mode of the O–N and N–C bonds. The analysis of the UV–vis spectra showed that the maximum absorption wavelength of M01 is 334.80 nm and that of M02 is 375.37 nm; both located in the ultraviolet. The high values of first (
β
T
) and second (
γ
¯
) hyperpolarizability showed that both molecules have very good nonlinear optical properties and thus can be used for second and third harmonic generation.
•BACN is thermodynamically and chemically stable.•BACN is a good organic semiconductor and has excellent hole transport properties.•BACN exhibits good optoelectronic and nonlinear optical ...properties.•BACN is fluorescent, it can improve colour purity of OLED and be used as an emitter.
In this study, we investigate the structural, vibrational, electronic, optical, transport, and thermodynamic properties of pure BACN using density functional theory (DFT). The B3LYP, B3PW91, CAM-B3LYP and ωB97XD functionals associated with the basis sets 6-31G(d,p) and 6-311G(d,p) were used. With regard to the electronic and transport properties, analysis of the HOMO and LUMO frontier orbitals, the gap values obtained and the reorganisation energies show that BACN is a good donor-acceptor semiconductor and has a good hole transport capacity. The study of non-linear optical properties shows that BACN is a good candidate for applications in nonlinear optics (NLO) because of its first-order hyperpolarisability, which is higher than that of urea. The time density functional theory (TD-DFT) approach was used for the photophysical analysis of BACN. It was found that BACN exhibits a maximum absorption in the near-UV range, peaking at 222.42 nm, and strong emission in the near-UV range with a maximum wavelength value of 229.75 nm through TD-CAM-B3LYP/6-311G(d,p). The Stokes shift values obtained indicate that the molecule is chemically stable. The full width at half-maximum (FWHM) and radiative lifetime values for this molecule are 19.924 nm and 16.071 ns, respectively. These results show that BACN is a fluorescent material that can be used as an emitter material for designing and improving the colour purity of organic light-emitting diodes (OLEDs).
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A microstructural approach to the prediction of heat flux transport in porous geopolymers is used experimentally to understand the effects of the pore size distribution and pores connectivity to the ...transfer of the thermal flux across the porous network of geopolymers. Controlling the mix design and the concentration of porogen agent, capillary pores can be introduced into the system for a final homogeneous microstructure. The roundness of pores, their geometrical distribution, and their connectivity allow the possibility to extend the length of the pathway of the tortuous route for potential heat flux. The nonlinear relationship between tortuosity–porosity and tortuosity–thermal conductivity confirms that the volume of pores is not the only parameter affecting the heat flux transport. The results achieved in terms of homogeneous microstructure with geometric description of pore, their level of isolation, and the spatial distribution allow the prediction of the heat flux transport in environmentally friendly and sustainable porous geopolymer materials.
Using density functional theory, we have studied the intrinsic properties of styrene. First, we determine the optimized structures, structural parameters and thermodynamic properties to make our ...simulations more realistic to experimental results and check the stability. Second, we investigate optoelectronic, electronic and global descriptors, transport properties of holes and electrons, natural bond orbital analysis, absorption and fluorescence properties. Finally, we study nonlinear optical (NLO) properties: first- and second-order hyperpolarizability, second and third-order optical susceptibilities, hyper-Rayleigh scattering hyperpolarizability, electro-optical Pockel effect, direct current Kerr effects and quadratic refractive index. The bandgap energy E g = 5.146 eV and dielectric constant ε r = 3.062 show that styrene is a good insulator with an average electric field value of 4.43 × 10 8 Vm −1 . Thermodynamic findings show that our molecule is thermodynamically and chemically stable. Electron and hole reorganization energies of 0.393 and 0.295 eV, respectively, show that styrene is more favourable to hole transport than electron transport. Styrene is transparent with linear refractive index n = 1.750 and quadratic n 2 = 1.748 × 10 −20 m 2 W −1 . At the NLO, styrene has a non-zero value of β H R S , which confirms the existence of first-order NLO activity. Globally the study shows that the styrene monomer is suitable for the architecture design of new polymer materials for NLO applications and optoelectronic by functionalization.
In this paper, the ground-state geometries and energies of Aln(n ≤ 170) clusters have been investigated using the Gupta potential combined with the molecular dynamics simulation quenching method. ...The Gupta parameters have been fixed according to the experimental values of the cohesive energy and lattice parameters. For each minimum, the energy and point group (PG) have been obtained. Our optimized structures are in agreement with previous ones obtained using Murrell-Mottram Potential as well as those obtained using the Glue potential. A simple relation between the ground state energy and the number of atoms has been proposed which can permit one to predict the ground state for any structure size with a known number of atoms. Display omitted
In this paper, the ground-state geometries and energies of AℓN(N⩽170) clusters have been investigated using the Gupta potential combined with the molecular dynamics simulation quenching method. The Gupta parameters have been fixed according to the experimental values of the cohesive energy and lattice parameters. For each minimum, the energy and point group (PG) have been obtained. Our optimized structures are in agreement with previous ones obtained using Murrell-Mottram potential as well as those obtained using the Glue potential. A simple relation between the ground state energy and the number of atoms has been proposed which can permit one to predict the ground state for any Aluminum cluster with a known number of atoms.
Material processing with laser offers a reliable tool in a large variety of micromachining technology, ranging from on-disc inscriptions to cell ablations through DNA combing and imprinting for ...fabrications of micro and nanofluidic devices. In these applications lasers are designed to operate in specific regimes characterized by their powers and wavelengths, so understanding characteristic properties of the distinct possible laser operation regimes turns out to be a relevant step toward optimization of their uses as well as improvement of the technology. In this work we examine the stability of a model of femtosecond laser intended for laser inscriptions in nonlinear transparent media, taking into consideration the laser-induced material damage and multiphoton ionization. The model approximates the laser dynamics by a complex Ginzburg–Landau equation with a Kerr plus a high-order nonlinear term accounting for K-photon ionization, coupled to a Drude equation for time evolution of the electron plasma density. Following the Benjamin–Feir instability theory it is shown that depending on characteristic parameters of the model, multiphoton ionization processes can stabilize continuous-wave or pulse regimes. These parameters include the group-delay dispersion, the linear and nonlinear gains, the phase shift per roundtrip and the plasma ionization rate.
