Molecular dynamics analysis of the crystallization of an overcooled aluminum melt

The homogeneous nucleation of a crystal in an overcooled aluminum melt was modeled by the molecular dynamics (MD) method. The MD simulation used the embedded-atom potential. The crystallization delay times were determined from MD simulation data. In a set of systems at the same temperature and pressure, the lifetimes were distributed exponentially. Nucleation frequencies at different temperatures and pressures were determined. The resulting nucleation frequencies were compared with the ones predicted by classical nucleation theory.     

Coherent control of the route of an ultrafast magnetic phase transition via low-amplitude spin precession

Time-resolved magneto-optical imaging of laser-excited rare-earth orthoferrite (SmPr)FeO3 demonstrates that a single 60 fs circularly polarized laser pulse is capable of creating a magnetic domain on a picosecond time scale with a magnetization direction determined by the helicity of light. Depending on the light intensity and sample temperature, pulses of the same helicity can create domains with opposite magnetizations. We argue that this phenomenon relies on a twofold effect of light which (i) instantaneously excites coherent low-amplitude spin precession and (ii) triggers a spin reorientation phase transition. The former dynamically breaks the equivalence between two otherwise degenerate states with opposite magnetizations in the high-temperature phase and thus controls the route of the phase transition.     

Hydrogen permeability through sandwich membranes

The problem of hydrogen permeability through sandwich membranes and membranes with nonhomogeneous (by depth) properties as the limiting case of permeability through a sandwich membrane when the thickness of the layers tends to zero is considered. The equation of permeability through sandwich membranes and nonhomogeneous membranes in the steady-state regime is obtained. Analytical dependencies of the permeability reduction factor in four limiting cases are found.     

Magnetic-field induced second harmonic generation in CuB2O4

Three types of optical magnetic-field induced second harmonic (MFISH) generation are observed in CuB2O4. Unusually sharp and intense electronic transitions in MFISH and linear absorption spectra provide selective access to the two nonequivalent Cu2+ sublattices. The magnetic phase diagram for both sublattices is determined by MFISH. Magnetic structure is dominated by antiferromagnetic order at the 4b site. Sublattice interactions transfer it to the 8d site where it coexists with a discoupled paramagnetic component.     

Working group report: Heavy-ion physics and quark-gluon plasma

This is the report of Heavy Ion Physics and Quark-Gluon Plasma at WHEPP-09 which was part of Working Group-4. Discussion and work on some aspects of quark-gluon plasma believed to have created in heavy-ion collisions and in early Universe are reported.     

Phase equilibrium and interdiffusion in the oligo(3,3-bis(azidomethyl)oxetane)-oligo(3-methyl-3-azidomethyloxetane) system

Intersolubility and interdiffusion in the oligo(3,3-bis(azidomethyl)oxetane)-oligo(3-methyl-3-azidomethyloxetane) binary system are studied. The components of the system differ in symmetric and non-symmetric positions of azide groups along the polymer chain, respectively. The chemical and conformational features ensure the ability of oligo(3,3-bis(azidomethyl)oxetane) to crystallize at temperatures of ∼50°C. The system of azidooxetane oligomers is characterized by a simple crystalline equilibrium crystal-melt. The generalized phase diagram of the binary system is constructed. The interdiffusion zones of oligomers are analyzed in detail in a wide temperature range, and a number of specific effects manifesting themselves during their intersolubility are observed. The concentration and temperature dependences of diffusion coefficients are examined, and the activation energies of diffusion are calculated.     

Corrosion of metal films in ice: the dynamics of the conductivity of films

A decrease in the conductivity of copper, aluminum, iron, and silver films brought in contact with ice as ice underwent thermally stimulated structural relaxation and of a copper film in contact with water undergoing crystallization was studied. Conductivity decrease was found to be irreversible and caused by metal corrosion.     

Influence of the Reaction Medium on the Kinetics of Copolymerization of N-Vinylsuccinimide with Butyl Acrylate

Radical copolymerization of N-vinylsuccinimide with n-butyl acrylate in pyridine and the influence of donor characteristics of the solvent on the reaction kinetics were studied. The kinetics of copolymerization in various solvents (dichloroethane, dimethyl sulfoxide, and pyridine) were studied.     

Electron acceleration during the breaking of an intense plasma wave in an inhomogeneous plasma

We investigate the dynamics of the electron acceleration when an intense plasma wave breaks near resonance at the plasma frequency (focus) in an inhomogeneous magnetized plasma. The breaking threshold has been determined. We compare our experimental dependences of the current and energy of fast electrons on the intensity of the incident wave at various times with theoretical estimates. We show that when the breaking threshold is significantly exceeded, up to 50% of the electrons at plasma resonance are captured and accelerated by the wave.