Synthesis and characterization of Ni magnetic nanoparticles in AlMCM41 host

Superparamagnetic nickel nanoparticles were prepared by incorporating nickel ion into AlMCM41 as a nanoreactor and then reduced with sodium borohydride or H₂ gas. Products were characterized by elemental analysis, transmission electron microscopy, X-ray powder diffraction, and magnetic susceptibility. The nickel particle size and blocking temperature depend on the reduction method.     

Hydrogen bonding in linear (LiH)2

Ab initio LCAO MO SCF calculations are reported on the linear form of LiH dimer. The properties and structure of the Li-H-Li linkage are discussed in the light of hydrogen bonding.     

j3Δg state of the hydrogen molecule

The potential energy curve for the j³Δ_g state of the hydrogen molecule has been calculated in the Born-Oppenheimer approximation. Highly flexible wavefunctions depending explicitly on the interelectronic distance have been used. The vibrational Schrödinger equation for the j state has been solved for H₂, HD, and D₂. The results are compared with the available experimental data, and it is shown that the adiabatic and nonadiabatic effects are mainly responsible for the existing discrepancy. The singlet-triplet separation for the j-J pair of states is also discussed.     

Analysis of the surface photovoltage under sub-bandgap illumination: Effect of the bulk traps

The simple theory of the surface photovoltage induced by photostimulated electron transitions from the bulk impurity levels is given. The relevant calculations show that the surface barrier height, the concentration of the impurity levels and the trapping process at the surface effectively control this phenomenon. Under the proper conditions, a very low excitation level in the bulk can generate significant surface photovoltage signals.     

Generation of the derivative of out-of-plane displacements in the high-sensitivity grating interferometry configuration

A simple method for determining the surface slope of a specimen under test in the high-sensitivity grating interferometry setup is proposed. The information on the derivative of out-of-plane displacement is obtained by software subtraction of two primary interferograms: a conventional one and one with diffraction orders laterally displaced in the image plane. Very good coincidence between the theoretical and experimental results has been obtained. The method can be used for studying static and transient events depending on the fringe pattern analysis method used.     

The electronic structure of the oxygen double-bridged μμ′-dioxo-bis(oxodichloroaquo)dimolybdate (V)-ion by SCCC MO method

Results of SCCC MO calculations for the dimeric oxygen double-bridged [Mo₂O₄Cl₄(H₂O)₂]^2–ion are reported. On the basis of these results the previously reported spectra and magnetic properties may be explained. The strong direct molybdenum — molybdenum interaction in the Mo₂O ₄ ²⁺ core was proved to exist.

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Zusammenfassung Die Ergebnisse von SCCC MO-Rechnungen für das zweikernige Ion [Mo₂O₄Cl₄(H₂O)₂]^2– mit zweifacher Sauerstoffbrücke werden mitgeteilt. Danach können die früher angeführten magnetischen und spektralen Eigenschaften dieses Ions verstanden werden. Die Existenz starker unmittelbarer Molybdän-Molybdän Wechselwirkungen innerhalb des Mo₂O ₄ ²⁺ Kerns wird nachgewiesen.

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Résumé Résultats de calculs SCCCMO pour l'ion dimère Mo₂O₄Cl₄(H₂O) ₂ ^2– . Sur la base de ces résultats les propriétés spectrales et magnétiques précédemment obtenues peuvent être expliquées. L'existence d'une forte interaction directe molybdène-molybdène dans le coeur Mo₂O ₄ ²⁺ est clairement démontrée.

     

Meso-[2.2]paracyclophanyltriphenylporphyrin: A simple representative of cyclophanylporphyrins

(R + S)Meso-[2.2]Paracyclophanyltriphenylporphyrin 3 , a member of a novel class of cyclophanylporphyrins, was obtained and characterized by spectroscopic and electrochemical methods. Compared to meso-tetra[2.2]paracyclophanylporphyrin 1, it represents a simplified structure designed for the investigation of electronic interactions between the [2.2]paracyclophane moiety and porphyrin core and for use in metallation reactions.     

Ab initio potential energy curves and vibrational levels for the c, l, and i states of the hydrogen molecule

Potential energy curves for the hydrogen molecule in the c³Π_u, I¹Π_g, and i³Π_g state have been calculated in the Born-Oppenheimer approximation. Highly flexible wavefunctions have been used, and for each state the calculations have been carried out for 40 different internuclear distances in the region 1 ≤ R ≤ 12 a.u. For the Π_g states the wavefunctions are known to change their character around R = 5 a.u. The effect of this change on various components of the energy has been analyzed. The vibrational Schrödinger equation for all states has been solved for H₂, HD, and D₂. For H₂ the resulting energies are compared with the experimental values and it is shown that the adiabatic effects are likely to be responsible for the existing discrepancy between the theoretical and experimental values.     

All-valence-electron and transition density matrix calculations of the electronic spectra of [2.2]paracyclophanequinones

The combined CNDO/S and transition density matrix methods reproduced well the UV-VIS spectra of the intramolecular charge-transfer complexes of double- and triple-layered [2.2]paracyclophanequinones in which benzene and p-benzoquinone represent the donor and acceptor layers: DA, DDA and DAD. Calculations pointed to the already known experimental bathochromic shifts of the longest wavelength absorption band for the DADDADAD transformations. The electronic transitions corresponding to this band are for DA and DDA the CT transitions of the ^* type; however, for DAD the band represents the n ^* transition localized on the acceptor ring.