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In certain conditions, plasma processes lead to the formation of a dispersed phase. A phase transformation is associated with the formation of a chemical bond and grouping of valence electrons of the surface and adsorbed atom, Pauli's principle being met. According to the experiment presented herein, nanoparticles generated from the plasma in laser-induced breakdown in a weak (80 mT) constant magnetic field, possess the smaller size than field-free nanoparticles. The paper studies processes affecting the nanoparticle size formed from the plasma in laser-induced breakdown in the weak constant magnetic field. [ABSTRACT FROM AUTHOR]

The localization of the valence electron of , and atoms enclosed by three different fullerene molecules is studied. The structure of the fullerene molecules is used to calculate the equilibrium position of the endohedrally atom as the minimum of the classical -body Lennard-Jones potential. Once the position of the guest atom is determined, the fullerene cavity is modeled by a short range attractive shell according to molecule symmetry, and the enclosed atom is modeled by an effective one-electron potential. In order to examine whether the endohedral compound is formed by a neutral atom inside a neutral fullerene molecule @ or if the valence electron of the encapsulated atom localizes in the fullerene giving rise to a state with the form @, we analyze the electronic density, the projections onto free atomic states and the weights of partial angular waves. [ABSTRACT FROM AUTHOR]

We discuss in detail the multiphoton absorption theory for wide bandgap dielectrics that we have implemented in the framework of the time-dependent Nth order perturbation theory. In particular, we have carried out calculations on the N-photon absorption coefficient KN and interband transition rate WN for a perfect sapphire crystal (α-Al2O3). Furthermore, we derive an expression on the laser-pulse induced seed electron density n0. Application of this theory on sapphire shows that n0, induced by the ultrashort laser pulse with pulse duration of 30 ps, wavelength of 1 μm, and peak intensity of 5 × 1011W/cm2 at the focus point, cannot lead to multiphoton-based ablation. Indeed, our calculations show that the laser pulse in the N = 7 order absorption process generates a conduction electron density n0 ≈ 6 × 1013 cm-3 that is far too small compared with the required critical density ncr ≈ 1019 - 1021 cm-3. This is in agreement with the extremely small value of the probability (Pind ≈ 2 × 10-9) that we have estimated for a valence electron to be transferred to the conduction band under the influence of the abovementioned laser-pulse conditions. Therefore, we need to seek other mechanisms than multiphoton absorption, to explain ablation in sapphire. However, we show that by using larger photon energies and smaller order N values, it is possible to induce large enough multiphoton absorption excited electron densities, which will lead to ablation in sapphire, even for the abovementioned laser beam intensity. Finally, we discuss the Keldysh adiabatic parameter y and its interpretation in the case of our experimental pulse-laser setup. [ABSTRACT FROM AUTHOR]

Abstract: The vertical core– and valence–shell electron excitation and ionization energies of the three title molecules, 1–3, were calculated by density functional theory (DFT) using adequate functional for each type of processes and atoms under study. The inner shells treated were C1s, N1s, S1s, S2s, S2p. Molecular geometry was optimized by DFT B3LYP/6-311+(d,p). The basis set of triple zeta plus polarization (TZP) Slater-type orbitals was employed for DFT calculations. The ΔSCF method was used to calculate ionization energies. The average absolute deviation (AAD) from experiment of 26 valence-electron ionization energies calculated by DFT for the three molecules 1–3 was 0.14eV; while that of 24 calculated core-electron binding energies (CEBEs) from experiment was 0.4eV. Selected core excitation energies were calculated by the multiplet approximation for the three molecules. The AAD of twelve calculated core excitation energies by the multiplet approximation that exclude S2s cases was 0.56eV. Time-dependent DFT (TDDFT) was employed to calculate the excitation energies and corresponding oscillator strengths of core- and valence-electrons of the molecules. Some selected occupied core orbitals were used to calculate the core-excitation energies with the TDDFT (Sterner–Frozoni–Simone scheme). The core excitation energies thus calculated were in an average error of ca. 28eV compared to observed values. They were shifted to the value calculated by the multiplet approximation. Convoluted spectra based upon the shifted energies and accompanying oscillator strengths reproduce low-energy region of observed spectra reasonably well, whereas they deviate from experiment in high-energy region. Reasonable agreement between theory and experiment was obtained for the valence electron excitations of the molecules. [Copyright &y& Elsevier]

• Valence Electron Ratio (VER) as a novel electron parameter of materials is introduced. • Martensitic transformation temperature decreases with increasing valence electron ratio of an alloy. • Valence electron ratio is the most dominant parameter controlling the transformation temperatures in shape memory alloys. • Transformation temperatures of AuTi -based and TiIr-based intermetallics sharply decrease with increasing their Valence electron ratio (VER). Dependence of transformation temperatures of TiAu- and TiIr-based Intermetallics on Valence Electron Ratio (VER), number of valence electrons (e v) and average atomic number of the alloys (Z) were investigated. The alloys mostly have medium numbers of valence electrons (6.5 ≤ e v ≤ 7.3) near 7 with a limited number of TiAu-based alloys belonging to high valence electron group with e v more than 7.50 and relatively narrow range of average atomic numbers (Z = 41–53). The forward and reverse phase transformation temperatures, M s and A s of AuTi-based alloys sharply increase with the average atomic number of the alloys. The investigated TiIr alloy compositions have almost similar average atomic numbers (49.5–50.2). Clear correlations between transformation temperatures and VER were found. M s and A s both decrease from around 1550 °C to as low as 17 °C respectively, with increasing VER from 0.131 to 0. 174. The dependence of transformation temperatures on valence electron ratio is discussed based on the variations of elastic properties and atomic bonding due to composition change in these alloys. [ABSTRACT FROM AUTHOR]

We have analyzed the electronic momentum distribution n( k) of sodium clusters using the Kohn-Sham formalism within the Local Density Approximation for the valence electrons. Simple approximations to the Wigner transform have been used to understand the deviation between n( k) in clusters and in the bulk system. Deformation effects have been also analyzed. [ABSTRACT FROM AUTHOR]