Electrical activation of optical transitions to parity-forbidden dark excitonic states in individual carbon nanotubes is reported. We examine electric-field effects on various excitonic states by ...simultaneously measuring photocurrent and photoluminescence. As the applied field increases, we observe an emergence of new absorption peaks in the excitation spectra. From the diameter dependence of the energy separation between the new peaks and the ground state of E 11 excitons, we attribute the peaks to the dark excited states which became optically active due to the applied field. Field-induced exciton dissociation can explain the photocurrent threshold field, and the edge of the E 11 continuum states has been identified by extrapolating to zero threshold.
Atmospheric tritium concentrations of HTO, HT and CH3T have been measured at Toki, Japan, for the environmental impact assessment of tritium for a fusion test facility. According to the data from ...2004 to 2012, the concentrations of HT and HTO in water vapour tend to increase in spring. The seasonal variation in HT concentration at Toki was compared with the H2 concentration between 1990 and 2005 at Tae-ahn Peninsula, Republic of Korea, which is at approximately the same latitude as Toki. The monthly average of HT-specific activity varied from 1.24 × 10(5) to 1.76 × 10(5) TU. The peak of the monthly average H2 concentration did not match that of HT. This indicates that the mechanism of the production or the source of HT might be different from the production mechanism of H2.
ZnSnP2 is a promising candidate as a solar absorbing material consisting of earth-abundant and low-toxic elements. In this study, the phosphidation method, where co-sputtered Zn–Sn thin films react ...with phosphorus gas, was adopted for fabricating ZnSnP2 thin films. To establish the conditions for producing ZnSnP2 thin films, we investigated the influence of phosphidation temperature on the product phases, and interpreted the experimental results using chemical potential diagrams of the Zn–Sn–P system. ZnSnP2 thin films with a single phase were obtained by phosphidation at 500°C under a phosphorus vapor pressure of 10−2atm. However, formation of ZnSnP2 protrusions was observed on the surface of the thin films. Based on the experimental results and the chemical potential diagrams, it is indicated that un-reacted liquid Sn particles reacted with Zn and phosphorus gas to form ZnSnP2 protrusions in a manner similar to the vapor-Liquid-Solid growth mode.
•We fabricated ZnSnP2 thin films as a solar absorber by phosphidation method.•We clarified the mechanism of morphology change during the phosphidation.•We demonstrated the utility of potential diagrams through the ZnSnP2 growth process.
Sn and Sn-based compounds have attracted great interest as candidates for anode materials in lithium-ion batteries. Despite the great deal of attention focused on the effects of the volume change of ...the Sn anode during the lithiation/delithiation process on the cyclic property of the batteries, its influence on the electrode potential is still not well understood. In this study, by constructing a simple Sn–Li battery system, we have investigated the effects of the volume change associated with the formation of Li–Sn compounds on the electrode potential from the viewpoint of the Gibbs free energy and associated elastic-strain energy. Our experimental results show that (i) α-Sn, which is a low-temperature phase and in thermodynamic non-equilibrium at around 298
K (our experimental temperature), is also formed together with usual β-Sn after several cycles of the lithiation and delithiation processes and (ii) when a Sn plate-shape electrode is lithiated, the experimental electrode potential underruns the value expected thermodynamically. These experimental results can be consistently explained by considering the contribution of the elastic-strain energy to the chemical free energy of formation.
Thermal decomposition of mixtures of poly(vinyl chloride) ( PVC) and a variety of metal oxides including rare earth oxides has been studied under helium atmosphere at 400 and 800
°C. Volatile ...pyrolysis products have been quantitatively analysed. The formation of benzene at 800
°C is suppressed by the addition of oxides except aluminium oxide, especially in the case of zinc oxide, reducing ∼80% compared with the case of pure PVC. The emission of hydrogen chloride changes significantly with the oxides used. This feature is strongly concerned with the chlorine fixing ability of oxides. Together with the analysis of pyrolysis residues, the behaviour of fixation of chlorine from PVC by oxides has been compared. The trivalent rare earth oxides (Ln
2O
3) show great ability to fix considerable amount (more than 95% in the case of lanthanum oxide) of initial chlorine in PVC in the form of oxychlorides (LnOCl). The water-insoluble property of LaOCl is advantageous for the use of La
2O
3, which is abundant in the sludge discharged from magnet production industry, as chlorine fixing agent.
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