Investigations of Bis-chromophore Systems: Relationship between Spectral Behaviour and Charge Transfer in 2-(3-coumaroyl)-benzopyrylium Perchlorates

The dependence of spectral properties and interfragmental charge transfer (ICT) on excitation, relaxation and excited state deactivation of 2-(3-cou­maroyl)-benzopyry­lium perchlorates has been analyzed. It was found that the positions of emission bands and rate constants of radiationless deactivation linearly correlate with ICT upon excited state deactivation, and Stokes’ shifts of fluorescence demonstrate linear dependence on ICT upon structural relaxation in the excited state

Spectral and Basic Properties of Flavones in the Ground and Excited States

Dependence between structures of R-oxyflavones and their spectral and basic properties has been investigated. It was found that pKa of flavones, depending on positions of hydroxy and methoxy groups, increase by 6-8 orders of magnitude upon excitation and reaches 3.7-6.6 units. Due to high pKa* value carbonyl group can serve as a proton acceptor in the excited-state intramolecular proton transfer as far as in the formation of phototautomers of 7- and 4'-hydroxyflavones in protic solvents

Hydrodynamic modeling of deconfinement phase transition in heavy-ion collisions at NICA-FAIR energies

We use (3+1) dimensional ideal hydrodynamics to describe the space-time evolution of strongly interacting matter created in Au+Au and Pb+Pb collisions. The model is applied for the domain of bombarding energies 1-160 AGeV which includes future NICA and FAIR experiments. Two equations of state are used: the first one corresponding to resonance hadron gas and the second one including the deconfinement phase transition. The initial state is represented by two Lorentz-boosted nuclei. Dynamical trajectories of matter in the central box of the system are analyzed. They can be well represented by a fast shock-wave compression followed by a relatively slow isentropic expansion. The parameters of collective flows and hadronic spectra are calculated under assumption of the isochronous freeze-out. It is shown that the deconfinement phase transition leads to broadening of proton rapidity distributions, increase of elliptic flows and formation of the directed antiflow in the central rapidity region. These effects are most pronounced at bombarding energies around 10 AGeV, when the system spends the longest time in the mixed phase. From the comparison with three-fluid calculations we conclude that the transparency effects are not so important in central collisions at NICA-FAIR energies (below 30 AGeV).Comment: 38 pages, 28 figure

Investigation of the Chaotic Dynamics of an Electron Beam with a Virtual Cathode in an External Magnetic Field

The effect of the strength of the focusing magnetic field on chaotic dynamic processes occurring inan electron beam with a virtual cathode, as well as on the processes whereby the structures form in the beamand interact with each other, is studied by means of two-dimensional numerical simulations based on solving a self-consistent set of Vlasov-Maxwell equations. It is shown that, as the focusing magnetic field is decreased,the dynamics of an electron beam with a virtual cathode becomes more complicated due to the formation andinteraction of spatio-temporal longitudinal and transverse structures in the interaction region of a vircator. The optimum efficiency of the interaction of an electron beam with the electromagnetic field of the vircator isachieved at a comparatively weak external magnetic field and is determined by the fundamentally two-dimensional nature of the motion of the beam electrons near the virtual cathode.Comment: 12 pages, 8 figure

Experimental and Theoretical Investigation into the Effect of the Electron Velocity Distribution on Chaotic Oscillations in an Electron Beam under Virtual Cathode Formation Conditions

The effect of the electron transverse and longitudinal velocity spread at the entrance to the interaction space on wide-band chaotic oscillations in intense multiple-velocity beams is studied theoretically and numerically under the conditions of formation of a virtual cathode. It is found that an increase in the electron velocity spread causes chaotization of virtual cathode oscillations. An insight into physical processes taking place in a virtual cathode multiple velocity beam is gained by numerical simulation. The chaotization of the oscillations is shown to be associated with additional electron structures, which were separated out by constructing charged particle distribution functions.Comment: 9 pages, 8 figure