China
Africa
Explore chapters and articles related to this topic
Borate Phosphors for Neutron Radiography
Published in S. K. Omanwar, R. P. Sonekar, N. S. Bajaj, Borate Phosphors, 2022
PSL of Ce3+ in alkali borate glasses of the composition 25R2O.75B2O3.0.5CeO2 ( R = Li, Na or K) had been studied earlier[116]. Maximum PSL was observed for K glasses. However, neutron imaging using these phosphors was not attempted. Valenca et al. [117] observed OSL in lithium-potassium mixed borosilcate glasses, as well as alkali borosilicate-MgO/CaO glasses [118], apparently even without using activator and found these glasses useful for dosimetry. On the other hand, Sroda et al. [119] found that Ce doping improved OSL sensitivity of barium borate glasses. The enhancement was attributed to the traps provided by Ce4+ which reduced to trivalent state by electron capture. However, no efforts to make NIP were made in these experiments.
High Harmonic Generation
Published in Hitendra K. Malik, Laser-Matter Interaction for Radiation and Energy, 2021
The basic phenomenon of THG is similar to that of SHG. In THG, three similar frequency photons are interacted with a nonlinear material, and there is an involvement of third-order nonlinear susceptibility (χ(3)). The mathematical model required to theoretically describe the THG is explained in detail in Section 8.7.1, and their detailed applications are discussed in Section 8.7.2. If the frequency of incident photons is different, then the preferred term is four-wave mixing (FWM; see Section 8.8). Materials used for THG are nonlinear crystals like β-BaB2O4 (Barium Borate: BBO). Also, the generation of third harmonics is possible based on the membranes in microscopy. The higher-order HGs also are theoretically feasible, but due to the requirement of interaction of a greater number of the photons, it has a minuscule probability of occurrence. A considerable different mechanism is adopted for the generation of higher-order harmonics. The Nth HG process is depicted in Figure 8.3.
Nonlinear Optics
Published in Chunlei Guo, Subhash Chandra Singh, Handbook of Laser Technology and Applications, 2021
The output frequencies of an OPO are usually controlled by adjusting the orientation of the nonlinear mixing crystal to determine which set of frequencies ω1 and ω2 (with ω1 + ω2 = ω3) satisfy the phase-matching condition (Δk = 0). OPOs tend to be broadly tunable because the tuning range is limited only by the limits of transparency of the crystal and by the limits over which the phase-matching relation can be established. Optical parametric oscillation was first observed experimentally by Giordmaine and Miller [44]. Continuous-wave OPO operation was first achieved by Smith et al. [45]. Early work on OPOs has been reviewed by Byer and Herbst [47]. An important material for the construction of OPOs is beta-barium borate [46].
High-resolution spectroscopy of the
Published in Molecular Physics, 2020
M. Génévriez, D. Wehrli, F. Merkt
In the photoexcitation chamber, the molecular beam is intersected at right angles by the pulses from two Nd:YAG-pumped dye lasers. The first laser, hereafter called laser 1, is operated with the dye Styril 8 and its fundamental output is frequency tripled using two β-barium-borate (BBO) nonlinear crystals. The wave number of the frequency-tripled radiation can be continuously tuned in the range from 38,700 cm to 39,500 cm, its bandwidth is 0.15 cm and the pulse energy is 0.2 mJ. The second laser, hereafter called laser 2, is operated with the dye DCM and its fundamental output is frequency-doubled with a BBO crystal. The frequency-doubled output has a bandwidth lying below 0.1 cm, its pulse energy is attenuated to below to reduce power broadening, and its wave number can be continuously tuned in the range from 31,100 cm to 32,600 cm. Both lasers are linearly polarised along a direction perpendicular to the direction of propagation of the molecular beam. The wave numbers of the fundamental outputs of both dye lasers are measured with a commercial wave metre with a specified absolute accuracy of 0.02 cm.
Computational studies on nonlinear optical property of novel Wittig-based Schiff-base ligands and copper(II) complex
Published in Molecular Physics, 2018
Bathula Rajasekhar, Nidarshana Patowary, Danish K. Z., Toka Swu
Molecular-based nonlinear optical (NLO) materials are given much attention because of their promising applications in up-coming photonic and optoelectronic technologies. They have more advantages than the atomic-based materials such as LiNbO3, KH2PO4 (KDP), α-quartz (SiO2), gallium arsenide (GaAs) and β-barium borate (BBO) [1–8]. Schiff-base complexes are one among the NLO property exhibiting molecular-based materials which are derived from aldehyde/ketones and amines. They are prominent chromophores with significantly large nonlinear response [9–14] because of their (1) easy synthesis, (2) thermally stability, (3) active role in generating polarisation when coordinated to a metal ion and (4) low energy charge transitions [15–17]. Schiff-base coordination complexes show higher nonlinearity than the Schiff-bases because metal center can act as an electron acceptor or donor and it can enhance the intramolecular charge transfer [18]. To generate more unsymmetrical electron distribution in this type of complexes, Gradnaru et al. [19,20] synthesised unsymmetrical Schiff-base complexes. Among all Schiff-base coordination complexes, Ni(II) (closed shell system) Schiff-base complexes were studied extensively than any other [18], but De Bella et al. reported that unpaired electron system like radicals, open shell metal complexes like Cu(II), Co(II) Schiff-Base complexes have more β (hyperpolarisability) value indicating enhancement of nonlinearity [21–27].
Application of different magnetic intensities for the treatment of landfill leachate in Egypt
Published in Cogent Engineering, 2018
Raed S. Al-Wasify, Mohamed N. Ali, Shimaa R. Hamed
Landfill leachate is characterized usually by offensive odor and complex chemical composition. It contains high concentrations of ammonia-nitrogen (NH3-N) content, heavy metals, inorganic salts and other organic materials (Ismail & Tawfik, 2016). However, landfill leachate may contain other compounds such as sulfide, barium, borate, arsenate, lithium, cobalt and mercury (Kjeldsen et al., 2002). If these pollutants left without proper control and treatment, it can reach the groundwater and cause serious damage to groundwater aquifers. Consequently, the presence of proper systems for collection and treatment of municipal landfill leachate is essential to reduce the environmental impacts and meet legislated standards for safe discharge into natural water streams or recycling (Nartey, Hayford, & Ametsi, 2012).