Laser-induced interference, focusing, and diffraction of rescattering molecular photoelectrons

We solve the time-dependent Schr?dinger equation in three dimensions for H+2 in a one-cycle laser pulse of moderate intensity. We consider fixed nuclear positions and Coulomb electron-nuclear interaction potentials. We analyze the field-induced electron interference and diffraction patterns. To extract the ionization dynamics we subtract the excitations to low-lying bound states explicitly. We follow the time evolution of a well-defined wave packet that is formed near the first peak of the laser field. We observe the fragmentation of the wave packet due to molecular focusing. We show how to retrieve a diffraction molecular image by taking the ratio of the momentum distributions in the two lateral directions. The positions of the diffraction peaks are well described by the classical double slit diffraction rule.     

Influence of a Magnetic Field on the Nonlinear Optical Susceptibility of NiI2-Doped CdI2 Single Crystals

The influence of treatment in a magnetic field at low temperatures on the nonlinear optical properties of NiI₂-doped CdI₂ single crystals is investigated. The impurity ions in the interlayer space or more complex centers into which these ions enter can align on exposure to a magnetic field due to the interaction with the membrane vibrations of the lattice and create residual polarization in a specimen. This polarization causes redistribution of the electric charge on the bonds and improves the nonlinear optical properties of single crystals.     

Theoretical ROVibrational Energies (TROVE): A robust numerical approach to the calculation of rovibrational energies for polyatomic molecules

We present a new computational method with associated computer program TROVE (Theoretical ROVibrational Energies) to perform variational calculations of rovibrational energies for general polyatomic molecules of arbitrary structure in isolated electronic states. The (approximate) nuclear kinetic energy operator is represented as an expansion in terms of internal coordinates. The main feature of the computational scheme is a numerical construction of the kinetic energy operator, which is an integral part of the computation process. Thus the scheme is self-contained, i.e., it requires no analytical pre-derivation of the kinetic energy operator. It is also general, since it can be used in connection with any internal coordinates. The method represents an extension of our model for pyramidal XY₃ molecules reported previously [S.N. Yurchenko, M. Carvajal, P. Jensen, H. Lin, J.J. Zheng, W. Thiel, Mol. Phys. 103 (2005) 359]. Non-rigid molecules are treated in the Hougen-Bunker-Johns approach [J.T. Hougen, P.R. Bunker, J.W.C. Johns, J. Mol. Spectrosc. 34 (1970) 136]. In this case, the variational calculations employ a numerical finite basis representation for the large-amplitude motion using basis functions that are generated by Numerov-Cooley integration of the appropriate one-dimensional Schrödinger equation.     

On the behaviour of Eu oxo-species in molten NaBr–NaI (0.77:0.23) mixture at 973 K

The interaction of Eu₂O₃ with molten NaBr–NaI (0.77:0.23) mixture at 973 K was studied by sequential addition method with the use of YSZ membrane oxygen electrode for controlling of course of the process. The Red-Ox process is accompanied with formation of EuO in the melt. The total solubility of EuO (sum of concentration of Eu²⁺, O^2–, non-dissociated EuO) in the molten NaBr–NaI at 973 K (mole fraction 2.7 × 10^–4) is considerably lower than in pure NaI melt (4.2 × 10^–4), which can be explained using the ‘hole’ model by reduction of a number of holes of comparable with EuO particle size because of addition of smaller bromide ion to the iodide melt.

The solubility of EuO is appreciably affected by its dispersity and the value of surface energy causing these solubility changes is estimated as 37 J m^–2.     

N-phosphorylated imidazolium salts as precursors to 2- and 5-phosphorylated imidazoles and new imidazol-2-ylidenes featuring the PNCN unit

It has been experimentally proven that the reaction of 1- or 1,2-disubstituted imidazoles with diorganylphosphorus(III) halides proceeds via initial formation of N-phosporylated imidazolium salts. Treatment of these salts with strong bases results in phosphorylation of the parent imidazoles at the 2- or 5-positions, correspondingly. In a previous case, imidazol-2-ylidenes are formed as intermediates. With both N1 and N3 atoms bearing sterically demanding or/and π-donating groups, deprotonation of 1,3-disubstituted imidazolium salts with NaN(SiMe(3))(2) afforded new stable N-phosphorus-substituted Arduengo-type carbenes.     

Quantum-chemical study of the electronic structure of adamantane and the 1-adamantyl cation,anion, and radical

The spatial and electronic structures of the adamantane molecule (AdH), the 1-adamantyl radical (1-Ad^.), the 1-adamantyl cation (1-AD⁺), and the 1-adamantyl anion (1-Ad^–) have been calculated by the SCF-MO-LCAO method in the all-valence-electron MINDO approximation. The calculated heats of formation attest to the fact that the homolytic cleavage of the C-H bond is energetically most advantageous in the gaseous phase or in nonpolar inert solvents. The formation of a 1-Ad^–, H⁺ pair is associated with the largest expenditure of energy due to the large ionization potential of the hydrogen atom.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 3, pp. 357–360, May–June, 1989.