Two mechanisms for fluorescence intermittency of single violamine R molecules

The environment and temperature-dependent photoluminescence (PL) intermittency or "blinking" demonstrated by single violamine R (VR) molecules is investigated in two environments: poly(vinyl alcohol) (PVOH) and single crystals of potassium acid phthalate (KAP). In addition, temperatures ranging from 23 °C to 85 °C are studied, spanning the glass-transition temperature of PVOH (T(g) = 72 °C). The PL intermittency exhibited by VR is analyzed using probability histograms of emissive and non-emissive periods. In both PVOH and KAP, these histograms are best fit by a power law, consistent with the kinetics for dark state production and decay being dispersed as observed in previous studies. However, these systems have different temperature dependences, signifying two different blinking mechanisms for VR. In PVOH, the on- and off-event probability histograms do not vary with temperature, consistent with electron transfer via tunneling between VR and the polymer. In KAP the same histograms are temperature dependent, and show that blinking slows down at higher temperatures. This result is inconsistent with an electron-transfer process being responsible for blinking. Instead, a non-adiabatic proton-transfer between VR and KAP is presented as a model consistent with this temperature dependence. In summary, the results presented here demonstrate that for a given luminophore, the photochemical processes responsible for PL intermittency can change with environment.     

Two-proton radioactivity of 45Fe

The decay of the extremely neutron-deficient isotope ⁴⁵Fe has been studied by using a new type of gaseous detector in which a technique of optical imaging is used to record tracks of charged particles. The two-proton radioactivity and the $ \beta$ -decay channels were clearly identified. For the first time, the angular and energy correlations between two protons emitted from the ⁴⁵Fe ground state were measured. The obtained results were confronted with predictions of a three-body model.     

Mössbauer and photocatalytic studies of CaFe2O4 nanoparticle-containing aluminosilicate prepared from domestic waste simulated slag

The relationship between local structure and visible-light activated photocatalytic effect of simulated domestic waste slag glass–ceramics (R-NaWSFe) was investigated. The largest pseudo-first-order rate constant of 9.75?×?10^?3 min^?1 was estimated for methylene blue decomposition test under the visible-light irradiation using R-NaWSFe with additional 30 mass% of Fe₂O₃ heat-treated at 900 °C for 100 min. The reason for the high photoactivity of this sample was mainly due to nanoparticles of CaFe₂O₄ and α-Fe₂O₃ confirmed by the Mössbauer spectrum measured at 77 K. It is concluded that the nanoparticles of magnetic components in silica are essential for exhibiting visible-light activated catalytic effect.

     

Heavy-ion inelastic scattering from deformed nuclei

Theoretical and experimental methods for studying heavy-ion inelastic scattering from deformed nuclei are described. The theoretical methods involve classical-limit approximations, while particle- γ-spectroseopy techniques are employed experimentally. With these approaches, heavy-ion excitation in the Coulomb-nuclear interference region acquires a transparent interpretation, despite the apparent complexity of the multistep excitation processes involved. The examples discussed provide a good illustration of the relationship between classical and quantum physics. The sensitivity of the inelastic scattering to details of the surface ion-ion potential due to radial and angular localization is exploited to provide a method of determining the equipotential contours in a direct manner which bypasses particular model-dependent parametrizations. The method is used to construct ion-ion potentials from inelastic scattering data for the systems ⁴⁰Ar + ¹⁶⁰Gd, ¹⁵⁶Gd, ¹⁶²Dy, ¹⁶⁴Dy, and¹⁸⁰Hf. The contribution of adiabatic giant resonance polarization to this potential is discussed. The relation between the deformed ion-ion potential and nuclear shapes is illustrated by comparing the experimental potentials to deformed double-folding and deformed proximity-potential calculations.     

Cross sections for charged current ν and\bar v interactions in the energy range 10 to 50 GeV

Charged-current neutrino and antineutrino interaction cross sections have been measured in the energy range 10 to 50 GeV using BEBC filled with a neon-hydrogen mixture. At these energies, σ/E was measured to be (0.73±0.08) 10^?38 cm²/GeV per nucleon for neutrinos and (0.32±0.06) 10^?38 cm²/GeV per nucleon for antineutrinos.     

Comment on Mach cones and magnetic forces in Saturn’s rings

We clarify the underlying physics of long-wavelength dust magnetoacoustic waves and short-wavelength (in comparison with the ion gyroradius ρ _i ) dust acoustic waves that are involved in the formation of Mach cones in the magnetized dusty plasma of Saturn’s rings.