Transient currents in a molecular photo-diode

Light-induced charge transmission through a molecular junction (molecular diode) is studied in the framework of a HOMO-LUMO model and in using a kinetic description. Expressions are presented for the sequential (hopping) and direct (tunneling) transient current components together with kinetic equations governing the time-dependent populations of the neutral and charged molecular states which participate in the current formation. Resonant and off-resonant charge transmission processes are analyzed in detail. It is demonstrated that the transient currents are associated with a molecular charging process which is initiated by photo excitation of the molecule. If the coupling of the molecule to the electrodes is strongly asymmetric the transient currents can significantly exceed the steady state current.Comment: 17 pages, 12 figures, accepted for publication in Chemical Physic

Novel mechanism for temperature-independent transitions in flexible molecules: role of thermodynamic fluctuations

Novel physical mechanism is proposed for explanation of temperature-independent transition reactions in molecular systems. The mechanism becomes effective in the case of conformation transitions between quasi-isoenergetic molecular states. It is shown that at room temperatures, stochastic broadening of molecular energy levels predominates the energy of low frequency vibrations accompanying the transition. This leads to a cancellation of temperature dependence in the stochastically averaged rate constants. As an example, physical interpretation of temperature-independent onset of P2X_3 receptor desensitization in neuronal membranes is provided.Comment: 4 pages, 1 figur

Novel superconducting phases of Tl-based compounds

Several new superconducting phases of the Tl-based compounds were prepared. Structural studies revealed cell lengths of 31.9 A and longer. Properties of Ce-containing compounds are also discussed